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linux/drivers/tty/serial/amba-pl011.c
Guennadi Liakhovetski c25a1ad707 serial: pl011: fix fall back from DMA to interrupt mode 
When falling back from DMA to interrupt mode the receive interrupt has to
be re-enabled to catch new incoming data.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-12-17 09:36:23 -08:00

2261 lines
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/*
* Driver for AMBA serial ports
*
* Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
*
* Copyright 1999 ARM Limited
* Copyright (C) 2000 Deep Blue Solutions Ltd.
* Copyright (C) 2010 ST-Ericsson SA
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* This is a generic driver for ARM AMBA-type serial ports. They
* have a lot of 16550-like features, but are not register compatible.
* Note that although they do have CTS, DCD and DSR inputs, they do
* not have an RI input, nor do they have DTR or RTS outputs. If
* required, these have to be supplied via some other means (eg, GPIO)
* and hooked into this driver.
*/
#if defined(CONFIG_SERIAL_AMBA_PL011_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
#define SUPPORT_SYSRQ
#endif
#include <linux/module.h>
#include <linux/ioport.h>
#include <linux/init.h>
#include <linux/console.h>
#include <linux/sysrq.h>
#include <linux/device.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/serial_core.h>
#include <linux/serial.h>
#include <linux/amba/bus.h>
#include <linux/amba/serial.h>
#include <linux/clk.h>
#include <linux/slab.h>
#include <linux/dmaengine.h>
#include <linux/dma-mapping.h>
#include <linux/scatterlist.h>
#include <linux/delay.h>
#include <linux/types.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/pinctrl/consumer.h>
#include <linux/sizes.h>
#include <linux/io.h>
#define UART_NR 14
#define SERIAL_AMBA_MAJOR 204
#define SERIAL_AMBA_MINOR 64
#define SERIAL_AMBA_NR UART_NR
#define AMBA_ISR_PASS_LIMIT 256
#define UART_DR_ERROR (UART011_DR_OE|UART011_DR_BE|UART011_DR_PE|UART011_DR_FE)
#define UART_DUMMY_DR_RX (1 << 16)
/* There is by now at least one vendor with differing details, so handle it */
struct vendor_data {
unsigned int ifls;
unsigned int lcrh_tx;
unsigned int lcrh_rx;
bool oversampling;
bool dma_threshold;
bool cts_event_workaround;
unsigned int (*get_fifosize)(struct amba_device *dev);
};
static unsigned int get_fifosize_arm(struct amba_device *dev)
{
return amba_rev(dev) < 3 ? 16 : 32;
}
static struct vendor_data vendor_arm = {
.ifls = UART011_IFLS_RX4_8|UART011_IFLS_TX4_8,
.lcrh_tx = UART011_LCRH,
.lcrh_rx = UART011_LCRH,
.oversampling = false,
.dma_threshold = false,
.cts_event_workaround = false,
.get_fifosize = get_fifosize_arm,
};
static unsigned int get_fifosize_st(struct amba_device *dev)
{
return 64;
}
static struct vendor_data vendor_st = {
.ifls = UART011_IFLS_RX_HALF|UART011_IFLS_TX_HALF,
.lcrh_tx = ST_UART011_LCRH_TX,
.lcrh_rx = ST_UART011_LCRH_RX,
.oversampling = true,
.dma_threshold = true,
.cts_event_workaround = true,
.get_fifosize = get_fifosize_st,
};
/* Deals with DMA transactions */
struct pl011_sgbuf {
struct scatterlist sg;
char *buf;
};
struct pl011_dmarx_data {
struct dma_chan *chan;
struct completion complete;
bool use_buf_b;
struct pl011_sgbuf sgbuf_a;
struct pl011_sgbuf sgbuf_b;
dma_cookie_t cookie;
bool running;
struct timer_list timer;
unsigned int last_residue;
unsigned long last_jiffies;
bool auto_poll_rate;
unsigned int poll_rate;
unsigned int poll_timeout;
};
struct pl011_dmatx_data {
struct dma_chan *chan;
struct scatterlist sg;
char *buf;
bool queued;
};
/*
* We wrap our port structure around the generic uart_port.
*/
struct uart_amba_port {
struct uart_port port;
struct clk *clk;
const struct vendor_data *vendor;
unsigned int dmacr; /* dma control reg */
unsigned int im; /* interrupt mask */
unsigned int old_status;
unsigned int fifosize; /* vendor-specific */
unsigned int lcrh_tx; /* vendor-specific */
unsigned int lcrh_rx; /* vendor-specific */
unsigned int old_cr; /* state during shutdown */
bool autorts;
char type[12];
#ifdef CONFIG_DMA_ENGINE
/* DMA stuff */
bool using_tx_dma;
bool using_rx_dma;
struct pl011_dmarx_data dmarx;
struct pl011_dmatx_data dmatx;
#endif
};
/*
* Reads up to 256 characters from the FIFO or until it's empty and
* inserts them into the TTY layer. Returns the number of characters
* read from the FIFO.
*/
static int pl011_fifo_to_tty(struct uart_amba_port *uap)
{
u16 status, ch;
unsigned int flag, max_count = 256;
int fifotaken = 0;
while (max_count--) {
status = readw(uap->port.membase + UART01x_FR);
if (status & UART01x_FR_RXFE)
break;
/* Take chars from the FIFO and update status */
ch = readw(uap->port.membase + UART01x_DR) |
UART_DUMMY_DR_RX;
flag = TTY_NORMAL;
uap->port.icount.rx++;
fifotaken++;
if (unlikely(ch & UART_DR_ERROR)) {
if (ch & UART011_DR_BE) {
ch &= ~(UART011_DR_FE | UART011_DR_PE);
uap->port.icount.brk++;
if (uart_handle_break(&uap->port))
continue;
} else if (ch & UART011_DR_PE)
uap->port.icount.parity++;
else if (ch & UART011_DR_FE)
uap->port.icount.frame++;
if (ch & UART011_DR_OE)
uap->port.icount.overrun++;
ch &= uap->port.read_status_mask;
if (ch & UART011_DR_BE)
flag = TTY_BREAK;
else if (ch & UART011_DR_PE)
flag = TTY_PARITY;
else if (ch & UART011_DR_FE)
flag = TTY_FRAME;
}
if (uart_handle_sysrq_char(&uap->port, ch & 255))
continue;
uart_insert_char(&uap->port, ch, UART011_DR_OE, ch, flag);
}
return fifotaken;
}
/*
* All the DMA operation mode stuff goes inside this ifdef.
* This assumes that you have a generic DMA device interface,
* no custom DMA interfaces are supported.
*/
#ifdef CONFIG_DMA_ENGINE
#define PL011_DMA_BUFFER_SIZE PAGE_SIZE
static int pl011_sgbuf_init(struct dma_chan *chan, struct pl011_sgbuf *sg,
enum dma_data_direction dir)
{
dma_addr_t dma_addr;
sg->buf = dma_alloc_coherent(chan->device->dev,
PL011_DMA_BUFFER_SIZE, &dma_addr, GFP_KERNEL);
if (!sg->buf)
return -ENOMEM;
sg_init_table(&sg->sg, 1);
sg_set_page(&sg->sg, phys_to_page(dma_addr),
PL011_DMA_BUFFER_SIZE, offset_in_page(dma_addr));
sg_dma_address(&sg->sg) = dma_addr;
return 0;
}
static void pl011_sgbuf_free(struct dma_chan *chan, struct pl011_sgbuf *sg,
enum dma_data_direction dir)
{
if (sg->buf) {
dma_free_coherent(chan->device->dev,
PL011_DMA_BUFFER_SIZE, sg->buf,
sg_dma_address(&sg->sg));
}
}
static void pl011_dma_probe_initcall(struct device *dev, struct uart_amba_port *uap)
{
/* DMA is the sole user of the platform data right now */
struct amba_pl011_data *plat = dev_get_platdata(uap->port.dev);
struct dma_slave_config tx_conf = {
.dst_addr = uap->port.mapbase + UART01x_DR,
.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE,
.direction = DMA_MEM_TO_DEV,
.dst_maxburst = uap->fifosize >> 1,
.device_fc = false,
};
struct dma_chan *chan;
dma_cap_mask_t mask;
chan = dma_request_slave_channel(dev, "tx");
if (!chan) {
/* We need platform data */
if (!plat || !plat->dma_filter) {
dev_info(uap->port.dev, "no DMA platform data\n");
return;
}
/* Try to acquire a generic DMA engine slave TX channel */
dma_cap_zero(mask);
dma_cap_set(DMA_SLAVE, mask);
chan = dma_request_channel(mask, plat->dma_filter,
plat->dma_tx_param);
if (!chan) {
dev_err(uap->port.dev, "no TX DMA channel!\n");
return;
}
}
dmaengine_slave_config(chan, &tx_conf);
uap->dmatx.chan = chan;
dev_info(uap->port.dev, "DMA channel TX %s\n",
dma_chan_name(uap->dmatx.chan));
/* Optionally make use of an RX channel as well */
chan = dma_request_slave_channel(dev, "rx");
if (!chan && plat->dma_rx_param) {
chan = dma_request_channel(mask, plat->dma_filter, plat->dma_rx_param);
if (!chan) {
dev_err(uap->port.dev, "no RX DMA channel!\n");
return;
}
}
if (chan) {
struct dma_slave_config rx_conf = {
.src_addr = uap->port.mapbase + UART01x_DR,
.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE,
.direction = DMA_DEV_TO_MEM,
.src_maxburst = uap->fifosize >> 1,
.device_fc = false,
};
dmaengine_slave_config(chan, &rx_conf);
uap->dmarx.chan = chan;
if (plat && plat->dma_rx_poll_enable) {
/* Set poll rate if specified. */
if (plat->dma_rx_poll_rate) {
uap->dmarx.auto_poll_rate = false;
uap->dmarx.poll_rate = plat->dma_rx_poll_rate;
} else {
/*
* 100 ms defaults to poll rate if not
* specified. This will be adjusted with
* the baud rate at set_termios.
*/
uap->dmarx.auto_poll_rate = true;
uap->dmarx.poll_rate = 100;
}
/* 3 secs defaults poll_timeout if not specified. */
if (plat->dma_rx_poll_timeout)
uap->dmarx.poll_timeout =
plat->dma_rx_poll_timeout;
else
uap->dmarx.poll_timeout = 3000;
} else
uap->dmarx.auto_poll_rate = false;
dev_info(uap->port.dev, "DMA channel RX %s\n",
dma_chan_name(uap->dmarx.chan));
}
}
#ifndef MODULE
/*
* Stack up the UARTs and let the above initcall be done at device
* initcall time, because the serial driver is called as an arch
* initcall, and at this time the DMA subsystem is not yet registered.
* At this point the driver will switch over to using DMA where desired.
*/
struct dma_uap {
struct list_head node;
struct uart_amba_port *uap;
struct device *dev;
};
static LIST_HEAD(pl011_dma_uarts);
static int __init pl011_dma_initcall(void)
{
struct list_head *node, *tmp;
list_for_each_safe(node, tmp, &pl011_dma_uarts) {
struct dma_uap *dmau = list_entry(node, struct dma_uap, node);
pl011_dma_probe_initcall(dmau->dev, dmau->uap);
list_del(node);
kfree(dmau);
}
return 0;
}
device_initcall(pl011_dma_initcall);
static void pl011_dma_probe(struct device *dev, struct uart_amba_port *uap)
{
struct dma_uap *dmau = kzalloc(sizeof(struct dma_uap), GFP_KERNEL);
if (dmau) {
dmau->uap = uap;
dmau->dev = dev;
list_add_tail(&dmau->node, &pl011_dma_uarts);
}
}
#else
static void pl011_dma_probe(struct device *dev, struct uart_amba_port *uap)
{
pl011_dma_probe_initcall(dev, uap);
}
#endif
static void pl011_dma_remove(struct uart_amba_port *uap)
{
/* TODO: remove the initcall if it has not yet executed */
if (uap->dmatx.chan)
dma_release_channel(uap->dmatx.chan);
if (uap->dmarx.chan)
dma_release_channel(uap->dmarx.chan);
}
/* Forward declare this for the refill routine */
static int pl011_dma_tx_refill(struct uart_amba_port *uap);
/*
* The current DMA TX buffer has been sent.
* Try to queue up another DMA buffer.
*/
static void pl011_dma_tx_callback(void *data)
{
struct uart_amba_port *uap = data;
struct pl011_dmatx_data *dmatx = &uap->dmatx;
unsigned long flags;
u16 dmacr;
spin_lock_irqsave(&uap->port.lock, flags);
if (uap->dmatx.queued)
dma_unmap_sg(dmatx->chan->device->dev, &dmatx->sg, 1,
DMA_TO_DEVICE);
dmacr = uap->dmacr;
uap->dmacr = dmacr & ~UART011_TXDMAE;
writew(uap->dmacr, uap->port.membase + UART011_DMACR);
/*
* If TX DMA was disabled, it means that we've stopped the DMA for
* some reason (eg, XOFF received, or we want to send an X-char.)
*
* Note: we need to be careful here of a potential race between DMA
* and the rest of the driver - if the driver disables TX DMA while
* a TX buffer completing, we must update the tx queued status to
* get further refills (hence we check dmacr).
*/
if (!(dmacr & UART011_TXDMAE) || uart_tx_stopped(&uap->port) ||
uart_circ_empty(&uap->port.state->xmit)) {
uap->dmatx.queued = false;
spin_unlock_irqrestore(&uap->port.lock, flags);
return;
}
if (pl011_dma_tx_refill(uap) <= 0) {
/*
* We didn't queue a DMA buffer for some reason, but we
* have data pending to be sent. Re-enable the TX IRQ.
*/
uap->im |= UART011_TXIM;
writew(uap->im, uap->port.membase + UART011_IMSC);
}
spin_unlock_irqrestore(&uap->port.lock, flags);
}
/*
* Try to refill the TX DMA buffer.
* Locking: called with port lock held and IRQs disabled.
* Returns:
* 1 if we queued up a TX DMA buffer.
* 0 if we didn't want to handle this by DMA
* <0 on error
*/
static int pl011_dma_tx_refill(struct uart_amba_port *uap)
{
struct pl011_dmatx_data *dmatx = &uap->dmatx;
struct dma_chan *chan = dmatx->chan;
struct dma_device *dma_dev = chan->device;
struct dma_async_tx_descriptor *desc;
struct circ_buf *xmit = &uap->port.state->xmit;
unsigned int count;
/*
* Try to avoid the overhead involved in using DMA if the
* transaction fits in the first half of the FIFO, by using
* the standard interrupt handling. This ensures that we
* issue a uart_write_wakeup() at the appropriate time.
*/
count = uart_circ_chars_pending(xmit);
if (count < (uap->fifosize >> 1)) {
uap->dmatx.queued = false;
return 0;
}
/*
* Bodge: don't send the last character by DMA, as this
* will prevent XON from notifying us to restart DMA.
*/
count -= 1;
/* Else proceed to copy the TX chars to the DMA buffer and fire DMA */
if (count > PL011_DMA_BUFFER_SIZE)
count = PL011_DMA_BUFFER_SIZE;
if (xmit->tail < xmit->head)
memcpy(&dmatx->buf[0], &xmit->buf[xmit->tail], count);
else {
size_t first = UART_XMIT_SIZE - xmit->tail;
size_t second = xmit->head;
memcpy(&dmatx->buf[0], &xmit->buf[xmit->tail], first);
if (second)
memcpy(&dmatx->buf[first], &xmit->buf[0], second);
}
dmatx->sg.length = count;
if (dma_map_sg(dma_dev->dev, &dmatx->sg, 1, DMA_TO_DEVICE) != 1) {
uap->dmatx.queued = false;
dev_dbg(uap->port.dev, "unable to map TX DMA\n");
return -EBUSY;
}
desc = dmaengine_prep_slave_sg(chan, &dmatx->sg, 1, DMA_MEM_TO_DEV,
DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
if (!desc) {
dma_unmap_sg(dma_dev->dev, &dmatx->sg, 1, DMA_TO_DEVICE);
uap->dmatx.queued = false;
/*
* If DMA cannot be used right now, we complete this
* transaction via IRQ and let the TTY layer retry.
*/
dev_dbg(uap->port.dev, "TX DMA busy\n");
return -EBUSY;
}
/* Some data to go along to the callback */
desc->callback = pl011_dma_tx_callback;
desc->callback_param = uap;
/* All errors should happen at prepare time */
dmaengine_submit(desc);
/* Fire the DMA transaction */
dma_dev->device_issue_pending(chan);
uap->dmacr |= UART011_TXDMAE;
writew(uap->dmacr, uap->port.membase + UART011_DMACR);
uap->dmatx.queued = true;
/*
* Now we know that DMA will fire, so advance the ring buffer
* with the stuff we just dispatched.
*/
xmit->tail = (xmit->tail + count) & (UART_XMIT_SIZE - 1);
uap->port.icount.tx += count;
if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
uart_write_wakeup(&uap->port);
return 1;
}
/*
* We received a transmit interrupt without a pending X-char but with
* pending characters.
* Locking: called with port lock held and IRQs disabled.
* Returns:
* false if we want to use PIO to transmit
* true if we queued a DMA buffer
*/
static bool pl011_dma_tx_irq(struct uart_amba_port *uap)
{
if (!uap->using_tx_dma)
return false;
/*
* If we already have a TX buffer queued, but received a
* TX interrupt, it will be because we've just sent an X-char.
* Ensure the TX DMA is enabled and the TX IRQ is disabled.
*/
if (uap->dmatx.queued) {
uap->dmacr |= UART011_TXDMAE;
writew(uap->dmacr, uap->port.membase + UART011_DMACR);
uap->im &= ~UART011_TXIM;
writew(uap->im, uap->port.membase + UART011_IMSC);
return true;
}
/*
* We don't have a TX buffer queued, so try to queue one.
* If we successfully queued a buffer, mask the TX IRQ.
*/
if (pl011_dma_tx_refill(uap) > 0) {
uap->im &= ~UART011_TXIM;
writew(uap->im, uap->port.membase + UART011_IMSC);
return true;
}
return false;
}
/*
* Stop the DMA transmit (eg, due to received XOFF).
* Locking: called with port lock held and IRQs disabled.
*/
static inline void pl011_dma_tx_stop(struct uart_amba_port *uap)
{
if (uap->dmatx.queued) {
uap->dmacr &= ~UART011_TXDMAE;
writew(uap->dmacr, uap->port.membase + UART011_DMACR);
}
}
/*
* Try to start a DMA transmit, or in the case of an XON/OFF
* character queued for send, try to get that character out ASAP.
* Locking: called with port lock held and IRQs disabled.
* Returns:
* false if we want the TX IRQ to be enabled
* true if we have a buffer queued
*/
static inline bool pl011_dma_tx_start(struct uart_amba_port *uap)
{
u16 dmacr;
if (!uap->using_tx_dma)
return false;
if (!uap->port.x_char) {
/* no X-char, try to push chars out in DMA mode */
bool ret = true;
if (!uap->dmatx.queued) {
if (pl011_dma_tx_refill(uap) > 0) {
uap->im &= ~UART011_TXIM;
ret = true;
} else {
uap->im |= UART011_TXIM;
ret = false;
}
writew(uap->im, uap->port.membase + UART011_IMSC);
} else if (!(uap->dmacr & UART011_TXDMAE)) {
uap->dmacr |= UART011_TXDMAE;
writew(uap->dmacr,
uap->port.membase + UART011_DMACR);
}
return ret;
}
/*
* We have an X-char to send. Disable DMA to prevent it loading
* the TX fifo, and then see if we can stuff it into the FIFO.
*/
dmacr = uap->dmacr;
uap->dmacr &= ~UART011_TXDMAE;
writew(uap->dmacr, uap->port.membase + UART011_DMACR);
if (readw(uap->port.membase + UART01x_FR) & UART01x_FR_TXFF) {
/*
* No space in the FIFO, so enable the transmit interrupt
* so we know when there is space. Note that once we've
* loaded the character, we should just re-enable DMA.
*/
return false;
}
writew(uap->port.x_char, uap->port.membase + UART01x_DR);
uap->port.icount.tx++;
uap->port.x_char = 0;
/* Success - restore the DMA state */
uap->dmacr = dmacr;
writew(dmacr, uap->port.membase + UART011_DMACR);
return true;
}
/*
* Flush the transmit buffer.
* Locking: called with port lock held and IRQs disabled.
*/
static void pl011_dma_flush_buffer(struct uart_port *port)
__releases(&uap->port.lock)
__acquires(&uap->port.lock)
{
struct uart_amba_port *uap = (struct uart_amba_port *)port;
if (!uap->using_tx_dma)
return;
/* Avoid deadlock with the DMA engine callback */
spin_unlock(&uap->port.lock);
dmaengine_terminate_all(uap->dmatx.chan);
spin_lock(&uap->port.lock);
if (uap->dmatx.queued) {
dma_unmap_sg(uap->dmatx.chan->device->dev, &uap->dmatx.sg, 1,
DMA_TO_DEVICE);
uap->dmatx.queued = false;
uap->dmacr &= ~UART011_TXDMAE;
writew(uap->dmacr, uap->port.membase + UART011_DMACR);
}
}
static void pl011_dma_rx_callback(void *data);
static int pl011_dma_rx_trigger_dma(struct uart_amba_port *uap)
{
struct dma_chan *rxchan = uap->dmarx.chan;
struct pl011_dmarx_data *dmarx = &uap->dmarx;
struct dma_async_tx_descriptor *desc;
struct pl011_sgbuf *sgbuf;
if (!rxchan)
return -EIO;
/* Start the RX DMA job */
sgbuf = uap->dmarx.use_buf_b ?
&uap->dmarx.sgbuf_b : &uap->dmarx.sgbuf_a;
desc = dmaengine_prep_slave_sg(rxchan, &sgbuf->sg, 1,
DMA_DEV_TO_MEM,
DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
/*
* If the DMA engine is busy and cannot prepare a
* channel, no big deal, the driver will fall back
* to interrupt mode as a result of this error code.
*/
if (!desc) {
uap->dmarx.running = false;
dmaengine_terminate_all(rxchan);
return -EBUSY;
}
/* Some data to go along to the callback */
desc->callback = pl011_dma_rx_callback;
desc->callback_param = uap;
dmarx->cookie = dmaengine_submit(desc);
dma_async_issue_pending(rxchan);
uap->dmacr |= UART011_RXDMAE;
writew(uap->dmacr, uap->port.membase + UART011_DMACR);
uap->dmarx.running = true;
uap->im &= ~UART011_RXIM;
writew(uap->im, uap->port.membase + UART011_IMSC);
return 0;
}
/*
* This is called when either the DMA job is complete, or
* the FIFO timeout interrupt occurred. This must be called
* with the port spinlock uap->port.lock held.
*/
static void pl011_dma_rx_chars(struct uart_amba_port *uap,
u32 pending, bool use_buf_b,
bool readfifo)
{
struct tty_port *port = &uap->port.state->port;
struct pl011_sgbuf *sgbuf = use_buf_b ?
&uap->dmarx.sgbuf_b : &uap->dmarx.sgbuf_a;
int dma_count = 0;
u32 fifotaken = 0; /* only used for vdbg() */
struct pl011_dmarx_data *dmarx = &uap->dmarx;
int dmataken = 0;
if (uap->dmarx.poll_rate) {
/* The data can be taken by polling */
dmataken = sgbuf->sg.length - dmarx->last_residue;
/* Recalculate the pending size */
if (pending >= dmataken)
pending -= dmataken;
}
/* Pick the remain data from the DMA */
if (pending) {
/*
* First take all chars in the DMA pipe, then look in the FIFO.
* Note that tty_insert_flip_buf() tries to take as many chars
* as it can.
*/
dma_count = tty_insert_flip_string(port, sgbuf->buf + dmataken,
pending);
uap->port.icount.rx += dma_count;
if (dma_count < pending)
dev_warn(uap->port.dev,
"couldn't insert all characters (TTY is full?)\n");
}
/* Reset the last_residue for Rx DMA poll */
if (uap->dmarx.poll_rate)
dmarx->last_residue = sgbuf->sg.length;
/*
* Only continue with trying to read the FIFO if all DMA chars have
* been taken first.
*/
if (dma_count == pending && readfifo) {
/* Clear any error flags */
writew(UART011_OEIS | UART011_BEIS | UART011_PEIS | UART011_FEIS,
uap->port.membase + UART011_ICR);
/*
* If we read all the DMA'd characters, and we had an
* incomplete buffer, that could be due to an rx error, or
* maybe we just timed out. Read any pending chars and check
* the error status.
*
* Error conditions will only occur in the FIFO, these will
* trigger an immediate interrupt and stop the DMA job, so we
* will always find the error in the FIFO, never in the DMA
* buffer.
*/
fifotaken = pl011_fifo_to_tty(uap);
}
spin_unlock(&uap->port.lock);
dev_vdbg(uap->port.dev,
"Took %d chars from DMA buffer and %d chars from the FIFO\n",
dma_count, fifotaken);
tty_flip_buffer_push(port);
spin_lock(&uap->port.lock);
}
static void pl011_dma_rx_irq(struct uart_amba_port *uap)
{
struct pl011_dmarx_data *dmarx = &uap->dmarx;
struct dma_chan *rxchan = dmarx->chan;
struct pl011_sgbuf *sgbuf = dmarx->use_buf_b ?
&dmarx->sgbuf_b : &dmarx->sgbuf_a;
size_t pending;
struct dma_tx_state state;
enum dma_status dmastat;
/*
* Pause the transfer so we can trust the current counter,
* do this before we pause the PL011 block, else we may
* overflow the FIFO.
*/
if (dmaengine_pause(rxchan))
dev_err(uap->port.dev, "unable to pause DMA transfer\n");
dmastat = rxchan->device->device_tx_status(rxchan,
dmarx->cookie, &state);
if (dmastat != DMA_PAUSED)
dev_err(uap->port.dev, "unable to pause DMA transfer\n");
/* Disable RX DMA - incoming data will wait in the FIFO */
uap->dmacr &= ~UART011_RXDMAE;
writew(uap->dmacr, uap->port.membase + UART011_DMACR);
uap->dmarx.running = false;
pending = sgbuf->sg.length - state.residue;
BUG_ON(pending > PL011_DMA_BUFFER_SIZE);
/* Then we terminate the transfer - we now know our residue */
dmaengine_terminate_all(rxchan);
/*
* This will take the chars we have so far and insert
* into the framework.
*/
pl011_dma_rx_chars(uap, pending, dmarx->use_buf_b, true);
/* Switch buffer & re-trigger DMA job */
dmarx->use_buf_b = !dmarx->use_buf_b;
if (pl011_dma_rx_trigger_dma(uap)) {
dev_dbg(uap->port.dev, "could not retrigger RX DMA job "
"fall back to interrupt mode\n");
uap->im |= UART011_RXIM;
writew(uap->im, uap->port.membase + UART011_IMSC);
}
}
static void pl011_dma_rx_callback(void *data)
{
struct uart_amba_port *uap = data;
struct pl011_dmarx_data *dmarx = &uap->dmarx;
struct dma_chan *rxchan = dmarx->chan;
bool lastbuf = dmarx->use_buf_b;
struct pl011_sgbuf *sgbuf = dmarx->use_buf_b ?
&dmarx->sgbuf_b : &dmarx->sgbuf_a;
size_t pending;
struct dma_tx_state state;
int ret;
/*
* This completion interrupt occurs typically when the
* RX buffer is totally stuffed but no timeout has yet
* occurred. When that happens, we just want the RX
* routine to flush out the secondary DMA buffer while
* we immediately trigger the next DMA job.
*/
spin_lock_irq(&uap->port.lock);
/*
* Rx data can be taken by the UART interrupts during
* the DMA irq handler. So we check the residue here.
*/
rxchan->device->device_tx_status(rxchan, dmarx->cookie, &state);
pending = sgbuf->sg.length - state.residue;
BUG_ON(pending > PL011_DMA_BUFFER_SIZE);
/* Then we terminate the transfer - we now know our residue */
dmaengine_terminate_all(rxchan);
uap->dmarx.running = false;
dmarx->use_buf_b = !lastbuf;
ret = pl011_dma_rx_trigger_dma(uap);
pl011_dma_rx_chars(uap, pending, lastbuf, false);
spin_unlock_irq(&uap->port.lock);
/*
* Do this check after we picked the DMA chars so we don't
* get some IRQ immediately from RX.
*/
if (ret) {
dev_dbg(uap->port.dev, "could not retrigger RX DMA job "
"fall back to interrupt mode\n");
uap->im |= UART011_RXIM;
writew(uap->im, uap->port.membase + UART011_IMSC);
}
}
/*
* Stop accepting received characters, when we're shutting down or
* suspending this port.
* Locking: called with port lock held and IRQs disabled.
*/
static inline void pl011_dma_rx_stop(struct uart_amba_port *uap)
{
/* FIXME. Just disable the DMA enable */
uap->dmacr &= ~UART011_RXDMAE;
writew(uap->dmacr, uap->port.membase + UART011_DMACR);
}
/*
* Timer handler for Rx DMA polling.
* Every polling, It checks the residue in the dma buffer and transfer
* data to the tty. Also, last_residue is updated for the next polling.
*/
static void pl011_dma_rx_poll(unsigned long args)
{
struct uart_amba_port *uap = (struct uart_amba_port *)args;
struct tty_port *port = &uap->port.state->port;
struct pl011_dmarx_data *dmarx = &uap->dmarx;
struct dma_chan *rxchan = uap->dmarx.chan;
unsigned long flags = 0;
unsigned int dmataken = 0;
unsigned int size = 0;
struct pl011_sgbuf *sgbuf;
int dma_count;
struct dma_tx_state state;
sgbuf = dmarx->use_buf_b ? &uap->dmarx.sgbuf_b : &uap->dmarx.sgbuf_a;
rxchan->device->device_tx_status(rxchan, dmarx->cookie, &state);
if (likely(state.residue < dmarx->last_residue)) {
dmataken = sgbuf->sg.length - dmarx->last_residue;
size = dmarx->last_residue - state.residue;
dma_count = tty_insert_flip_string(port, sgbuf->buf + dmataken,
size);
if (dma_count == size)
dmarx->last_residue = state.residue;
dmarx->last_jiffies = jiffies;
}
tty_flip_buffer_push(port);
/*
* If no data is received in poll_timeout, the driver will fall back
* to interrupt mode. We will retrigger DMA at the first interrupt.
*/
if (jiffies_to_msecs(jiffies - dmarx->last_jiffies)
> uap->dmarx.poll_timeout) {
spin_lock_irqsave(&uap->port.lock, flags);
pl011_dma_rx_stop(uap);
uap->im |= UART011_RXIM;
writew(uap->im, uap->port.membase + UART011_IMSC);
spin_unlock_irqrestore(&uap->port.lock, flags);
uap->dmarx.running = false;
dmaengine_terminate_all(rxchan);
del_timer(&uap->dmarx.timer);
} else {
mod_timer(&uap->dmarx.timer,
jiffies + msecs_to_jiffies(uap->dmarx.poll_rate));
}
}
static void pl011_dma_startup(struct uart_amba_port *uap)
{
int ret;
if (!uap->dmatx.chan)
return;
uap->dmatx.buf = kmalloc(PL011_DMA_BUFFER_SIZE, GFP_KERNEL);
if (!uap->dmatx.buf) {
dev_err(uap->port.dev, "no memory for DMA TX buffer\n");
uap->port.fifosize = uap->fifosize;
return;
}
sg_init_one(&uap->dmatx.sg, uap->dmatx.buf, PL011_DMA_BUFFER_SIZE);
/* The DMA buffer is now the FIFO the TTY subsystem can use */
uap->port.fifosize = PL011_DMA_BUFFER_SIZE;
uap->using_tx_dma = true;
if (!uap->dmarx.chan)
goto skip_rx;
/* Allocate and map DMA RX buffers */
ret = pl011_sgbuf_init(uap->dmarx.chan, &uap->dmarx.sgbuf_a,
DMA_FROM_DEVICE);
if (ret) {
dev_err(uap->port.dev, "failed to init DMA %s: %d\n",
"RX buffer A", ret);
goto skip_rx;
}
ret = pl011_sgbuf_init(uap->dmarx.chan, &uap->dmarx.sgbuf_b,
DMA_FROM_DEVICE);
if (ret) {
dev_err(uap->port.dev, "failed to init DMA %s: %d\n",
"RX buffer B", ret);
pl011_sgbuf_free(uap->dmarx.chan, &uap->dmarx.sgbuf_a,
DMA_FROM_DEVICE);
goto skip_rx;
}
uap->using_rx_dma = true;
skip_rx:
/* Turn on DMA error (RX/TX will be enabled on demand) */
uap->dmacr |= UART011_DMAONERR;
writew(uap->dmacr, uap->port.membase + UART011_DMACR);
/*
* ST Micro variants has some specific dma burst threshold
* compensation. Set this to 16 bytes, so burst will only
* be issued above/below 16 bytes.
*/
if (uap->vendor->dma_threshold)
writew(ST_UART011_DMAWM_RX_16 | ST_UART011_DMAWM_TX_16,
uap->port.membase + ST_UART011_DMAWM);
if (uap->using_rx_dma) {
if (pl011_dma_rx_trigger_dma(uap))
dev_dbg(uap->port.dev, "could not trigger initial "
"RX DMA job, fall back to interrupt mode\n");
if (uap->dmarx.poll_rate) {
init_timer(&(uap->dmarx.timer));
uap->dmarx.timer.function = pl011_dma_rx_poll;
uap->dmarx.timer.data = (unsigned long)uap;
mod_timer(&uap->dmarx.timer,
jiffies +
msecs_to_jiffies(uap->dmarx.poll_rate));
uap->dmarx.last_residue = PL011_DMA_BUFFER_SIZE;
uap->dmarx.last_jiffies = jiffies;
}
}
}
static void pl011_dma_shutdown(struct uart_amba_port *uap)
{
if (!(uap->using_tx_dma || uap->using_rx_dma))
return;
/* Disable RX and TX DMA */
while (readw(uap->port.membase + UART01x_FR) & UART01x_FR_BUSY)
barrier();
spin_lock_irq(&uap->port.lock);
uap->dmacr &= ~(UART011_DMAONERR | UART011_RXDMAE | UART011_TXDMAE);
writew(uap->dmacr, uap->port.membase + UART011_DMACR);
spin_unlock_irq(&uap->port.lock);
if (uap->using_tx_dma) {
/* In theory, this should already be done by pl011_dma_flush_buffer */
dmaengine_terminate_all(uap->dmatx.chan);
if (uap->dmatx.queued) {
dma_unmap_sg(uap->dmatx.chan->device->dev, &uap->dmatx.sg, 1,
DMA_TO_DEVICE);
uap->dmatx.queued = false;
}
kfree(uap->dmatx.buf);
uap->using_tx_dma = false;
}
if (uap->using_rx_dma) {
dmaengine_terminate_all(uap->dmarx.chan);
/* Clean up the RX DMA */
pl011_sgbuf_free(uap->dmarx.chan, &uap->dmarx.sgbuf_a, DMA_FROM_DEVICE);
pl011_sgbuf_free(uap->dmarx.chan, &uap->dmarx.sgbuf_b, DMA_FROM_DEVICE);
if (uap->dmarx.poll_rate)
del_timer_sync(&uap->dmarx.timer);
uap->using_rx_dma = false;
}
}
static inline bool pl011_dma_rx_available(struct uart_amba_port *uap)
{
return uap->using_rx_dma;
}
static inline bool pl011_dma_rx_running(struct uart_amba_port *uap)
{
return uap->using_rx_dma && uap->dmarx.running;
}
#else
/* Blank functions if the DMA engine is not available */
static inline void pl011_dma_probe(struct device *dev, struct uart_amba_port *uap)
{
}
static inline void pl011_dma_remove(struct uart_amba_port *uap)
{
}
static inline void pl011_dma_startup(struct uart_amba_port *uap)
{
}
static inline void pl011_dma_shutdown(struct uart_amba_port *uap)
{
}
static inline bool pl011_dma_tx_irq(struct uart_amba_port *uap)
{
return false;
}
static inline void pl011_dma_tx_stop(struct uart_amba_port *uap)
{
}
static inline bool pl011_dma_tx_start(struct uart_amba_port *uap)
{
return false;
}
static inline void pl011_dma_rx_irq(struct uart_amba_port *uap)
{
}
static inline void pl011_dma_rx_stop(struct uart_amba_port *uap)
{
}
static inline int pl011_dma_rx_trigger_dma(struct uart_amba_port *uap)
{
return -EIO;
}
static inline bool pl011_dma_rx_available(struct uart_amba_port *uap)
{
return false;
}
static inline bool pl011_dma_rx_running(struct uart_amba_port *uap)
{
return false;
}
#define pl011_dma_flush_buffer NULL
#endif
static void pl011_stop_tx(struct uart_port *port)
{
struct uart_amba_port *uap = (struct uart_amba_port *)port;
uap->im &= ~UART011_TXIM;
writew(uap->im, uap->port.membase + UART011_IMSC);
pl011_dma_tx_stop(uap);
}
static void pl011_start_tx(struct uart_port *port)
{
struct uart_amba_port *uap = (struct uart_amba_port *)port;
if (!pl011_dma_tx_start(uap)) {
uap->im |= UART011_TXIM;
writew(uap->im, uap->port.membase + UART011_IMSC);
}
}
static void pl011_stop_rx(struct uart_port *port)
{
struct uart_amba_port *uap = (struct uart_amba_port *)port;
uap->im &= ~(UART011_RXIM|UART011_RTIM|UART011_FEIM|
UART011_PEIM|UART011_BEIM|UART011_OEIM);
writew(uap->im, uap->port.membase + UART011_IMSC);
pl011_dma_rx_stop(uap);
}
static void pl011_enable_ms(struct uart_port *port)
{
struct uart_amba_port *uap = (struct uart_amba_port *)port;
uap->im |= UART011_RIMIM|UART011_CTSMIM|UART011_DCDMIM|UART011_DSRMIM;
writew(uap->im, uap->port.membase + UART011_IMSC);
}
static void pl011_rx_chars(struct uart_amba_port *uap)
__releases(&uap->port.lock)
__acquires(&uap->port.lock)
{
pl011_fifo_to_tty(uap);
spin_unlock(&uap->port.lock);
tty_flip_buffer_push(&uap->port.state->port);
/*
* If we were temporarily out of DMA mode for a while,
* attempt to switch back to DMA mode again.
*/
if (pl011_dma_rx_available(uap)) {
if (pl011_dma_rx_trigger_dma(uap)) {
dev_dbg(uap->port.dev, "could not trigger RX DMA job "
"fall back to interrupt mode again\n");
uap->im |= UART011_RXIM;
writew(uap->im, uap->port.membase + UART011_IMSC);
} else {
#ifdef CONFIG_DMA_ENGINE
/* Start Rx DMA poll */
if (uap->dmarx.poll_rate) {
uap->dmarx.last_jiffies = jiffies;
uap->dmarx.last_residue = PL011_DMA_BUFFER_SIZE;
mod_timer(&uap->dmarx.timer,
jiffies +
msecs_to_jiffies(uap->dmarx.poll_rate));
}
#endif
}
}
spin_lock(&uap->port.lock);
}
static void pl011_tx_chars(struct uart_amba_port *uap)
{
struct circ_buf *xmit = &uap->port.state->xmit;
int count;
if (uap->port.x_char) {
writew(uap->port.x_char, uap->port.membase + UART01x_DR);
uap->port.icount.tx++;
uap->port.x_char = 0;
return;
}
if (uart_circ_empty(xmit) || uart_tx_stopped(&uap->port)) {
pl011_stop_tx(&uap->port);
return;
}
/* If we are using DMA mode, try to send some characters. */
if (pl011_dma_tx_irq(uap))
return;
count = uap->fifosize >> 1;
do {
writew(xmit->buf[xmit->tail], uap->port.membase + UART01x_DR);
xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
uap->port.icount.tx++;
if (uart_circ_empty(xmit))
break;
} while (--count > 0);
if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
uart_write_wakeup(&uap->port);
if (uart_circ_empty(xmit))
pl011_stop_tx(&uap->port);
}
static void pl011_modem_status(struct uart_amba_port *uap)
{
unsigned int status, delta;
status = readw(uap->port.membase + UART01x_FR) & UART01x_FR_MODEM_ANY;
delta = status ^ uap->old_status;
uap->old_status = status;
if (!delta)
return;
if (delta & UART01x_FR_DCD)
uart_handle_dcd_change(&uap->port, status & UART01x_FR_DCD);
if (delta & UART01x_FR_DSR)
uap->port.icount.dsr++;
if (delta & UART01x_FR_CTS)
uart_handle_cts_change(&uap->port, status & UART01x_FR_CTS);
wake_up_interruptible(&uap->port.state->port.delta_msr_wait);
}
static irqreturn_t pl011_int(int irq, void *dev_id)
{
struct uart_amba_port *uap = dev_id;
unsigned long flags;
unsigned int status, pass_counter = AMBA_ISR_PASS_LIMIT;
int handled = 0;
unsigned int dummy_read;
spin_lock_irqsave(&uap->port.lock, flags);
status = readw(uap->port.membase + UART011_MIS);
if (status) {
do {
if (uap->vendor->cts_event_workaround) {
/* workaround to make sure that all bits are unlocked.. */
writew(0x00, uap->port.membase + UART011_ICR);
/*
* WA: introduce 26ns(1 uart clk) delay before W1C;
* single apb access will incur 2 pclk(133.12Mhz) delay,
* so add 2 dummy reads
*/
dummy_read = readw(uap->port.membase + UART011_ICR);
dummy_read = readw(uap->port.membase + UART011_ICR);
}
writew(status & ~(UART011_TXIS|UART011_RTIS|
UART011_RXIS),
uap->port.membase + UART011_ICR);
if (status & (UART011_RTIS|UART011_RXIS)) {
if (pl011_dma_rx_running(uap))
pl011_dma_rx_irq(uap);
else
pl011_rx_chars(uap);
}
if (status & (UART011_DSRMIS|UART011_DCDMIS|
UART011_CTSMIS|UART011_RIMIS))
pl011_modem_status(uap);
if (status & UART011_TXIS)
pl011_tx_chars(uap);
if (pass_counter-- == 0)
break;
status = readw(uap->port.membase + UART011_MIS);
} while (status != 0);
handled = 1;
}
spin_unlock_irqrestore(&uap->port.lock, flags);
return IRQ_RETVAL(handled);
}
static unsigned int pl011_tx_empty(struct uart_port *port)
{
struct uart_amba_port *uap = (struct uart_amba_port *)port;
unsigned int status = readw(uap->port.membase + UART01x_FR);
return status & (UART01x_FR_BUSY|UART01x_FR_TXFF) ? 0 : TIOCSER_TEMT;
}
static unsigned int pl011_get_mctrl(struct uart_port *port)
{
struct uart_amba_port *uap = (struct uart_amba_port *)port;
unsigned int result = 0;
unsigned int status = readw(uap->port.membase + UART01x_FR);
#define TIOCMBIT(uartbit, tiocmbit) \
if (status & uartbit) \
result |= tiocmbit
TIOCMBIT(UART01x_FR_DCD, TIOCM_CAR);
TIOCMBIT(UART01x_FR_DSR, TIOCM_DSR);
TIOCMBIT(UART01x_FR_CTS, TIOCM_CTS);
TIOCMBIT(UART011_FR_RI, TIOCM_RNG);
#undef TIOCMBIT
return result;
}
static void pl011_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
struct uart_amba_port *uap = (struct uart_amba_port *)port;
unsigned int cr;
cr = readw(uap->port.membase + UART011_CR);
#define TIOCMBIT(tiocmbit, uartbit) \
if (mctrl & tiocmbit) \
cr |= uartbit; \
else \
cr &= ~uartbit
TIOCMBIT(TIOCM_RTS, UART011_CR_RTS);
TIOCMBIT(TIOCM_DTR, UART011_CR_DTR);
TIOCMBIT(TIOCM_OUT1, UART011_CR_OUT1);
TIOCMBIT(TIOCM_OUT2, UART011_CR_OUT2);
TIOCMBIT(TIOCM_LOOP, UART011_CR_LBE);
if (uap->autorts) {
/* We need to disable auto-RTS if we want to turn RTS off */
TIOCMBIT(TIOCM_RTS, UART011_CR_RTSEN);
}
#undef TIOCMBIT
writew(cr, uap->port.membase + UART011_CR);
}
static void pl011_break_ctl(struct uart_port *port, int break_state)
{
struct uart_amba_port *uap = (struct uart_amba_port *)port;
unsigned long flags;
unsigned int lcr_h;
spin_lock_irqsave(&uap->port.lock, flags);
lcr_h = readw(uap->port.membase + uap->lcrh_tx);
if (break_state == -1)
lcr_h |= UART01x_LCRH_BRK;
else
lcr_h &= ~UART01x_LCRH_BRK;
writew(lcr_h, uap->port.membase + uap->lcrh_tx);
spin_unlock_irqrestore(&uap->port.lock, flags);
}
#ifdef CONFIG_CONSOLE_POLL
static void pl011_quiesce_irqs(struct uart_port *port)
{
struct uart_amba_port *uap = (struct uart_amba_port *)port;
unsigned char __iomem *regs = uap->port.membase;
writew(readw(regs + UART011_MIS), regs + UART011_ICR);
/*
* There is no way to clear TXIM as this is "ready to transmit IRQ", so
* we simply mask it. start_tx() will unmask it.
*
* Note we can race with start_tx(), and if the race happens, the
* polling user might get another interrupt just after we clear it.
* But it should be OK and can happen even w/o the race, e.g.
* controller immediately got some new data and raised the IRQ.
*
* And whoever uses polling routines assumes that it manages the device
* (including tx queue), so we're also fine with start_tx()'s caller
* side.
*/
writew(readw(regs + UART011_IMSC) & ~UART011_TXIM, regs + UART011_IMSC);
}
static int pl011_get_poll_char(struct uart_port *port)
{
struct uart_amba_port *uap = (struct uart_amba_port *)port;
unsigned int status;
/*
* The caller might need IRQs lowered, e.g. if used with KDB NMI
* debugger.
*/
pl011_quiesce_irqs(port);
status = readw(uap->port.membase + UART01x_FR);
if (status & UART01x_FR_RXFE)
return NO_POLL_CHAR;
return readw(uap->port.membase + UART01x_DR);
}
static void pl011_put_poll_char(struct uart_port *port,
unsigned char ch)
{
struct uart_amba_port *uap = (struct uart_amba_port *)port;
while (readw(uap->port.membase + UART01x_FR) & UART01x_FR_TXFF)
barrier();
writew(ch, uap->port.membase + UART01x_DR);
}
#endif /* CONFIG_CONSOLE_POLL */
static int pl011_hwinit(struct uart_port *port)
{
struct uart_amba_port *uap = (struct uart_amba_port *)port;
int retval;
/* Optionaly enable pins to be muxed in and configured */
pinctrl_pm_select_default_state(port->dev);
/*
* Try to enable the clock producer.
*/
retval = clk_prepare_enable(uap->clk);
if (retval)
goto out;
uap->port.uartclk = clk_get_rate(uap->clk);
/* Clear pending error and receive interrupts */
writew(UART011_OEIS | UART011_BEIS | UART011_PEIS | UART011_FEIS |
UART011_RTIS | UART011_RXIS, uap->port.membase + UART011_ICR);
/*
* Save interrupts enable mask, and enable RX interrupts in case if
* the interrupt is used for NMI entry.
*/
uap->im = readw(uap->port.membase + UART011_IMSC);
writew(UART011_RTIM | UART011_RXIM, uap->port.membase + UART011_IMSC);
if (dev_get_platdata(uap->port.dev)) {
struct amba_pl011_data *plat;
plat = dev_get_platdata(uap->port.dev);
if (plat->init)
plat->init();
}
return 0;
out:
return retval;
}
static void pl011_write_lcr_h(struct uart_amba_port *uap, unsigned int lcr_h)
{
writew(lcr_h, uap->port.membase + uap->lcrh_rx);
if (uap->lcrh_rx != uap->lcrh_tx) {
int i;
/*
* Wait 10 PCLKs before writing LCRH_TX register,
* to get this delay write read only register 10 times
*/
for (i = 0; i < 10; ++i)
writew(0xff, uap->port.membase + UART011_MIS);
writew(lcr_h, uap->port.membase + uap->lcrh_tx);
}
}
static int pl011_startup(struct uart_port *port)
{
struct uart_amba_port *uap = (struct uart_amba_port *)port;
unsigned int cr, lcr_h, fbrd, ibrd;
int retval;
retval = pl011_hwinit(port);
if (retval)
goto clk_dis;
writew(uap->im, uap->port.membase + UART011_IMSC);
/*
* Allocate the IRQ
*/
retval = request_irq(uap->port.irq, pl011_int, 0, "uart-pl011", uap);
if (retval)
goto clk_dis;
writew(uap->vendor->ifls, uap->port.membase + UART011_IFLS);
/*
* Provoke TX FIFO interrupt into asserting. Taking care to preserve
* baud rate and data format specified by FBRD, IBRD and LCRH as the
* UART may already be in use as a console.
*/
spin_lock_irq(&uap->port.lock);
fbrd = readw(uap->port.membase + UART011_FBRD);
ibrd = readw(uap->port.membase + UART011_IBRD);
lcr_h = readw(uap->port.membase + uap->lcrh_rx);
cr = UART01x_CR_UARTEN | UART011_CR_TXE | UART011_CR_LBE;
writew(cr, uap->port.membase + UART011_CR);
writew(0, uap->port.membase + UART011_FBRD);
writew(1, uap->port.membase + UART011_IBRD);
pl011_write_lcr_h(uap, 0);
writew(0, uap->port.membase + UART01x_DR);
while (readw(uap->port.membase + UART01x_FR) & UART01x_FR_BUSY)
barrier();
writew(fbrd, uap->port.membase + UART011_FBRD);
writew(ibrd, uap->port.membase + UART011_IBRD);
pl011_write_lcr_h(uap, lcr_h);
/* restore RTS and DTR */
cr = uap->old_cr & (UART011_CR_RTS | UART011_CR_DTR);
cr |= UART01x_CR_UARTEN | UART011_CR_RXE | UART011_CR_TXE;
writew(cr, uap->port.membase + UART011_CR);
spin_unlock_irq(&uap->port.lock);
/*
* initialise the old status of the modem signals
*/
uap->old_status = readw(uap->port.membase + UART01x_FR) & UART01x_FR_MODEM_ANY;
/* Startup DMA */
pl011_dma_startup(uap);
/*
* Finally, enable interrupts, only timeouts when using DMA
* if initial RX DMA job failed, start in interrupt mode
* as well.
*/
spin_lock_irq(&uap->port.lock);
/* Clear out any spuriously appearing RX interrupts */
writew(UART011_RTIS | UART011_RXIS,
uap->port.membase + UART011_ICR);
uap->im = UART011_RTIM;
if (!pl011_dma_rx_running(uap))
uap->im |= UART011_RXIM;
writew(uap->im, uap->port.membase + UART011_IMSC);
spin_unlock_irq(&uap->port.lock);
return 0;
clk_dis:
clk_disable_unprepare(uap->clk);
return retval;
}
static void pl011_shutdown_channel(struct uart_amba_port *uap,
unsigned int lcrh)
{
unsigned long val;
val = readw(uap->port.membase + lcrh);
val &= ~(UART01x_LCRH_BRK | UART01x_LCRH_FEN);
writew(val, uap->port.membase + lcrh);
}
static void pl011_shutdown(struct uart_port *port)
{
struct uart_amba_port *uap = (struct uart_amba_port *)port;
unsigned int cr;
/*
* disable all interrupts
*/
spin_lock_irq(&uap->port.lock);
uap->im = 0;
writew(uap->im, uap->port.membase + UART011_IMSC);
writew(0xffff, uap->port.membase + UART011_ICR);
spin_unlock_irq(&uap->port.lock);
pl011_dma_shutdown(uap);
/*
* Free the interrupt
*/
free_irq(uap->port.irq, uap);
/*
* disable the port
* disable the port. It should not disable RTS and DTR.
* Also RTS and DTR state should be preserved to restore
* it during startup().
*/
uap->autorts = false;
spin_lock_irq(&uap->port.lock);
cr = readw(uap->port.membase + UART011_CR);
uap->old_cr = cr;
cr &= UART011_CR_RTS | UART011_CR_DTR;
cr |= UART01x_CR_UARTEN | UART011_CR_TXE;
writew(cr, uap->port.membase + UART011_CR);
spin_unlock_irq(&uap->port.lock);
/*
* disable break condition and fifos
*/
pl011_shutdown_channel(uap, uap->lcrh_rx);
if (uap->lcrh_rx != uap->lcrh_tx)
pl011_shutdown_channel(uap, uap->lcrh_tx);
/*
* Shut down the clock producer
*/
clk_disable_unprepare(uap->clk);
/* Optionally let pins go into sleep states */
pinctrl_pm_select_sleep_state(port->dev);
if (dev_get_platdata(uap->port.dev)) {
struct amba_pl011_data *plat;
plat = dev_get_platdata(uap->port.dev);
if (plat->exit)
plat->exit();
}
}
static void
pl011_set_termios(struct uart_port *port, struct ktermios *termios,
struct ktermios *old)
{
struct uart_amba_port *uap = (struct uart_amba_port *)port;
unsigned int lcr_h, old_cr;
unsigned long flags;
unsigned int baud, quot, clkdiv;
if (uap->vendor->oversampling)
clkdiv = 8;
else
clkdiv = 16;
/*
* Ask the core to calculate the divisor for us.
*/
baud = uart_get_baud_rate(port, termios, old, 0,
port->uartclk / clkdiv);
#ifdef CONFIG_DMA_ENGINE
/*
* Adjust RX DMA polling rate with baud rate if not specified.
*/
if (uap->dmarx.auto_poll_rate)
uap->dmarx.poll_rate = DIV_ROUND_UP(10000000, baud);
#endif
if (baud > port->uartclk/16)
quot = DIV_ROUND_CLOSEST(port->uartclk * 8, baud);
else
quot = DIV_ROUND_CLOSEST(port->uartclk * 4, baud);
switch (termios->c_cflag & CSIZE) {
case CS5:
lcr_h = UART01x_LCRH_WLEN_5;
break;
case CS6:
lcr_h = UART01x_LCRH_WLEN_6;
break;
case CS7:
lcr_h = UART01x_LCRH_WLEN_7;
break;
default: // CS8
lcr_h = UART01x_LCRH_WLEN_8;
break;
}
if (termios->c_cflag & CSTOPB)
lcr_h |= UART01x_LCRH_STP2;
if (termios->c_cflag & PARENB) {
lcr_h |= UART01x_LCRH_PEN;
if (!(termios->c_cflag & PARODD))
lcr_h |= UART01x_LCRH_EPS;
}
if (uap->fifosize > 1)
lcr_h |= UART01x_LCRH_FEN;
spin_lock_irqsave(&port->lock, flags);
/*
* Update the per-port timeout.
*/
uart_update_timeout(port, termios->c_cflag, baud);
port->read_status_mask = UART011_DR_OE | 255;
if (termios->c_iflag & INPCK)
port->read_status_mask |= UART011_DR_FE | UART011_DR_PE;
if (termios->c_iflag & (BRKINT | PARMRK))
port->read_status_mask |= UART011_DR_BE;
/*
* Characters to ignore
*/
port->ignore_status_mask = 0;
if (termios->c_iflag & IGNPAR)
port->ignore_status_mask |= UART011_DR_FE | UART011_DR_PE;
if (termios->c_iflag & IGNBRK) {
port->ignore_status_mask |= UART011_DR_BE;
/*
* If we're ignoring parity and break indicators,
* ignore overruns too (for real raw support).
*/
if (termios->c_iflag & IGNPAR)
port->ignore_status_mask |= UART011_DR_OE;
}
/*
* Ignore all characters if CREAD is not set.
*/
if ((termios->c_cflag & CREAD) == 0)
port->ignore_status_mask |= UART_DUMMY_DR_RX;
if (UART_ENABLE_MS(port, termios->c_cflag))
pl011_enable_ms(port);
/* first, disable everything */
old_cr = readw(port->membase + UART011_CR);
writew(0, port->membase + UART011_CR);
if (termios->c_cflag & CRTSCTS) {
if (old_cr & UART011_CR_RTS)
old_cr |= UART011_CR_RTSEN;
old_cr |= UART011_CR_CTSEN;
uap->autorts = true;
} else {
old_cr &= ~(UART011_CR_CTSEN | UART011_CR_RTSEN);
uap->autorts = false;
}
if (uap->vendor->oversampling) {
if (baud > port->uartclk / 16)
old_cr |= ST_UART011_CR_OVSFACT;
else
old_cr &= ~ST_UART011_CR_OVSFACT;
}
/*
* Workaround for the ST Micro oversampling variants to
* increase the bitrate slightly, by lowering the divisor,
* to avoid delayed sampling of start bit at high speeds,
* else we see data corruption.
*/
if (uap->vendor->oversampling) {
if ((baud >= 3000000) && (baud < 3250000) && (quot > 1))
quot -= 1;
else if ((baud > 3250000) && (quot > 2))
quot -= 2;
}
/* Set baud rate */
writew(quot & 0x3f, port->membase + UART011_FBRD);
writew(quot >> 6, port->membase + UART011_IBRD);
/*
* ----------v----------v----------v----------v-----
* NOTE: lcrh_tx and lcrh_rx MUST BE WRITTEN AFTER
* UART011_FBRD & UART011_IBRD.
* ----------^----------^----------^----------^-----
*/
pl011_write_lcr_h(uap, lcr_h);
writew(old_cr, port->membase + UART011_CR);
spin_unlock_irqrestore(&port->lock, flags);
}
static const char *pl011_type(struct uart_port *port)
{
struct uart_amba_port *uap = (struct uart_amba_port *)port;
return uap->port.type == PORT_AMBA ? uap->type : NULL;
}
/*
* Release the memory region(s) being used by 'port'
*/
static void pl011_release_port(struct uart_port *port)
{
release_mem_region(port->mapbase, SZ_4K);
}
/*
* Request the memory region(s) being used by 'port'
*/
static int pl011_request_port(struct uart_port *port)
{
return request_mem_region(port->mapbase, SZ_4K, "uart-pl011")
!= NULL ? 0 : -EBUSY;
}
/*
* Configure/autoconfigure the port.
*/
static void pl011_config_port(struct uart_port *port, int flags)
{
if (flags & UART_CONFIG_TYPE) {
port->type = PORT_AMBA;
pl011_request_port(port);
}
}
/*
* verify the new serial_struct (for TIOCSSERIAL).
*/
static int pl011_verify_port(struct uart_port *port, struct serial_struct *ser)
{
int ret = 0;
if (ser->type != PORT_UNKNOWN && ser->type != PORT_AMBA)
ret = -EINVAL;
if (ser->irq < 0 || ser->irq >= nr_irqs)
ret = -EINVAL;
if (ser->baud_base < 9600)
ret = -EINVAL;
return ret;
}
static struct uart_ops amba_pl011_pops = {
.tx_empty = pl011_tx_empty,
.set_mctrl = pl011_set_mctrl,
.get_mctrl = pl011_get_mctrl,
.stop_tx = pl011_stop_tx,
.start_tx = pl011_start_tx,
.stop_rx = pl011_stop_rx,
.enable_ms = pl011_enable_ms,
.break_ctl = pl011_break_ctl,
.startup = pl011_startup,
.shutdown = pl011_shutdown,
.flush_buffer = pl011_dma_flush_buffer,
.set_termios = pl011_set_termios,
.type = pl011_type,
.release_port = pl011_release_port,
.request_port = pl011_request_port,
.config_port = pl011_config_port,
.verify_port = pl011_verify_port,
#ifdef CONFIG_CONSOLE_POLL
.poll_init = pl011_hwinit,
.poll_get_char = pl011_get_poll_char,
.poll_put_char = pl011_put_poll_char,
#endif
};
static struct uart_amba_port *amba_ports[UART_NR];
#ifdef CONFIG_SERIAL_AMBA_PL011_CONSOLE
static void pl011_console_putchar(struct uart_port *port, int ch)
{
struct uart_amba_port *uap = (struct uart_amba_port *)port;
while (readw(uap->port.membase + UART01x_FR) & UART01x_FR_TXFF)
barrier();
writew(ch, uap->port.membase + UART01x_DR);
}
static void
pl011_console_write(struct console *co, const char *s, unsigned int count)
{
struct uart_amba_port *uap = amba_ports[co->index];
unsigned int status, old_cr, new_cr;
unsigned long flags;
int locked = 1;
clk_enable(uap->clk);
local_irq_save(flags);
if (uap->port.sysrq)
locked = 0;
else if (oops_in_progress)
locked = spin_trylock(&uap->port.lock);
else
spin_lock(&uap->port.lock);
/*
* First save the CR then disable the interrupts
*/
old_cr = readw(uap->port.membase + UART011_CR);
new_cr = old_cr & ~UART011_CR_CTSEN;
new_cr |= UART01x_CR_UARTEN | UART011_CR_TXE;
writew(new_cr, uap->port.membase + UART011_CR);
uart_console_write(&uap->port, s, count, pl011_console_putchar);
/*
* Finally, wait for transmitter to become empty
* and restore the TCR
*/
do {
status = readw(uap->port.membase + UART01x_FR);
} while (status & UART01x_FR_BUSY);
writew(old_cr, uap->port.membase + UART011_CR);
if (locked)
spin_unlock(&uap->port.lock);
local_irq_restore(flags);
clk_disable(uap->clk);
}
static void __init
pl011_console_get_options(struct uart_amba_port *uap, int *baud,
int *parity, int *bits)
{
if (readw(uap->port.membase + UART011_CR) & UART01x_CR_UARTEN) {
unsigned int lcr_h, ibrd, fbrd;
lcr_h = readw(uap->port.membase + uap->lcrh_tx);
*parity = 'n';
if (lcr_h & UART01x_LCRH_PEN) {
if (lcr_h & UART01x_LCRH_EPS)
*parity = 'e';
else
*parity = 'o';
}
if ((lcr_h & 0x60) == UART01x_LCRH_WLEN_7)
*bits = 7;
else
*bits = 8;
ibrd = readw(uap->port.membase + UART011_IBRD);
fbrd = readw(uap->port.membase + UART011_FBRD);
*baud = uap->port.uartclk * 4 / (64 * ibrd + fbrd);
if (uap->vendor->oversampling) {
if (readw(uap->port.membase + UART011_CR)
& ST_UART011_CR_OVSFACT)
*baud *= 2;
}
}
}
static int __init pl011_console_setup(struct console *co, char *options)
{
struct uart_amba_port *uap;
int baud = 38400;
int bits = 8;
int parity = 'n';
int flow = 'n';
int ret;
/*
* Check whether an invalid uart number has been specified, and
* if so, search for the first available port that does have
* console support.
*/
if (co->index >= UART_NR)
co->index = 0;
uap = amba_ports[co->index];
if (!uap)
return -ENODEV;
/* Allow pins to be muxed in and configured */
pinctrl_pm_select_default_state(uap->port.dev);
ret = clk_prepare(uap->clk);
if (ret)
return ret;
if (dev_get_platdata(uap->port.dev)) {
struct amba_pl011_data *plat;
plat = dev_get_platdata(uap->port.dev);
if (plat->init)
plat->init();
}
uap->port.uartclk = clk_get_rate(uap->clk);
if (options)
uart_parse_options(options, &baud, &parity, &bits, &flow);
else
pl011_console_get_options(uap, &baud, &parity, &bits);
return uart_set_options(&uap->port, co, baud, parity, bits, flow);
}
static struct uart_driver amba_reg;
static struct console amba_console = {
.name = "ttyAMA",
.write = pl011_console_write,
.device = uart_console_device,
.setup = pl011_console_setup,
.flags = CON_PRINTBUFFER,
.index = -1,
.data = &amba_reg,
};
#define AMBA_CONSOLE (&amba_console)
#else
#define AMBA_CONSOLE NULL
#endif
static struct uart_driver amba_reg = {
.owner = THIS_MODULE,
.driver_name = "ttyAMA",
.dev_name = "ttyAMA",
.major = SERIAL_AMBA_MAJOR,
.minor = SERIAL_AMBA_MINOR,
.nr = UART_NR,
.cons = AMBA_CONSOLE,
};
static int pl011_probe_dt_alias(int index, struct device *dev)
{
struct device_node *np;
static bool seen_dev_with_alias = false;
static bool seen_dev_without_alias = false;
int ret = index;
if (!IS_ENABLED(CONFIG_OF))
return ret;
np = dev->of_node;
if (!np)
return ret;
ret = of_alias_get_id(np, "serial");
if (IS_ERR_VALUE(ret)) {
seen_dev_without_alias = true;
ret = index;
} else {
seen_dev_with_alias = true;
if (ret >= ARRAY_SIZE(amba_ports) || amba_ports[ret] != NULL) {
dev_warn(dev, "requested serial port %d not available.\n", ret);
ret = index;
}
}
if (seen_dev_with_alias && seen_dev_without_alias)
dev_warn(dev, "aliased and non-aliased serial devices found in device tree. Serial port enumeration may be unpredictable.\n");
return ret;
}
static int pl011_probe(struct amba_device *dev, const struct amba_id *id)
{
struct uart_amba_port *uap;
struct vendor_data *vendor = id->data;
void __iomem *base;
int i, ret;
for (i = 0; i < ARRAY_SIZE(amba_ports); i++)
if (amba_ports[i] == NULL)
break;
if (i == ARRAY_SIZE(amba_ports)) {
ret = -EBUSY;
goto out;
}
uap = devm_kzalloc(&dev->dev, sizeof(struct uart_amba_port),
GFP_KERNEL);
if (uap == NULL) {
ret = -ENOMEM;
goto out;
}
i = pl011_probe_dt_alias(i, &dev->dev);
base = devm_ioremap(&dev->dev, dev->res.start,
resource_size(&dev->res));
if (!base) {
ret = -ENOMEM;
goto out;
}
uap->clk = devm_clk_get(&dev->dev, NULL);
if (IS_ERR(uap->clk)) {
ret = PTR_ERR(uap->clk);
goto out;
}
uap->vendor = vendor;
uap->lcrh_rx = vendor->lcrh_rx;
uap->lcrh_tx = vendor->lcrh_tx;
uap->old_cr = 0;
uap->fifosize = vendor->get_fifosize(dev);
uap->port.dev = &dev->dev;
uap->port.mapbase = dev->res.start;
uap->port.membase = base;
uap->port.iotype = UPIO_MEM;
uap->port.irq = dev->irq[0];
uap->port.fifosize = uap->fifosize;
uap->port.ops = &amba_pl011_pops;
uap->port.flags = UPF_BOOT_AUTOCONF;
uap->port.line = i;
pl011_dma_probe(&dev->dev, uap);
/* Ensure interrupts from this UART are masked and cleared */
writew(0, uap->port.membase + UART011_IMSC);
writew(0xffff, uap->port.membase + UART011_ICR);
snprintf(uap->type, sizeof(uap->type), "PL011 rev%u", amba_rev(dev));
amba_ports[i] = uap;
amba_set_drvdata(dev, uap);
ret = uart_add_one_port(&amba_reg, &uap->port);
if (ret) {
amba_ports[i] = NULL;
pl011_dma_remove(uap);
}
out:
return ret;
}
static int pl011_remove(struct amba_device *dev)
{
struct uart_amba_port *uap = amba_get_drvdata(dev);
int i;
uart_remove_one_port(&amba_reg, &uap->port);
for (i = 0; i < ARRAY_SIZE(amba_ports); i++)
if (amba_ports[i] == uap)
amba_ports[i] = NULL;
pl011_dma_remove(uap);
return 0;
}
#ifdef CONFIG_PM_SLEEP
static int pl011_suspend(struct device *dev)
{
struct uart_amba_port *uap = dev_get_drvdata(dev);
if (!uap)
return -EINVAL;
return uart_suspend_port(&amba_reg, &uap->port);
}
static int pl011_resume(struct device *dev)
{
struct uart_amba_port *uap = dev_get_drvdata(dev);
if (!uap)
return -EINVAL;
return uart_resume_port(&amba_reg, &uap->port);
}
#endif
static SIMPLE_DEV_PM_OPS(pl011_dev_pm_ops, pl011_suspend, pl011_resume);
static struct amba_id pl011_ids[] = {
{
.id = 0x00041011,
.mask = 0x000fffff,
.data = &vendor_arm,
},
{
.id = 0x00380802,
.mask = 0x00ffffff,
.data = &vendor_st,
},
{ 0, 0 },
};
MODULE_DEVICE_TABLE(amba, pl011_ids);
static struct amba_driver pl011_driver = {
.drv = {
.name = "uart-pl011",
.pm = &pl011_dev_pm_ops,
},
.id_table = pl011_ids,
.probe = pl011_probe,
.remove = pl011_remove,
};
static int __init pl011_init(void)
{
int ret;
printk(KERN_INFO "Serial: AMBA PL011 UART driver\n");
ret = uart_register_driver(&amba_reg);
if (ret == 0) {
ret = amba_driver_register(&pl011_driver);
if (ret)
uart_unregister_driver(&amba_reg);
}
return ret;
}
static void __exit pl011_exit(void)
{
amba_driver_unregister(&pl011_driver);
uart_unregister_driver(&amba_reg);
}
/*
* While this can be a module, if builtin it's most likely the console
* So let's leave module_exit but move module_init to an earlier place
*/
arch_initcall(pl011_init);
module_exit(pl011_exit);
MODULE_AUTHOR("ARM Ltd/Deep Blue Solutions Ltd");
MODULE_DESCRIPTION("ARM AMBA serial port driver");
MODULE_LICENSE("GPL");
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