linux/drivers/clocksource/timer-imx-tpm.c

240 lines
5.5 KiB
C

/*
* Copyright 2016 Freescale Semiconductor, Inc.
* Copyright 2017 NXP
*
* 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.
*/
#include <linux/clk.h>
#include <linux/clockchips.h>
#include <linux/clocksource.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/sched_clock.h>
#define TPM_SC 0x10
#define TPM_SC_CMOD_INC_PER_CNT (0x1 << 3)
#define TPM_SC_CMOD_DIV_DEFAULT 0x3
#define TPM_CNT 0x14
#define TPM_MOD 0x18
#define TPM_STATUS 0x1c
#define TPM_STATUS_CH0F BIT(0)
#define TPM_C0SC 0x20
#define TPM_C0SC_CHIE BIT(6)
#define TPM_C0SC_MODE_SHIFT 2
#define TPM_C0SC_MODE_MASK 0x3c
#define TPM_C0SC_MODE_SW_COMPARE 0x4
#define TPM_C0V 0x24
static void __iomem *timer_base;
static struct clock_event_device clockevent_tpm;
static inline void tpm_timer_disable(void)
{
unsigned int val;
/* channel disable */
val = readl(timer_base + TPM_C0SC);
val &= ~(TPM_C0SC_MODE_MASK | TPM_C0SC_CHIE);
writel(val, timer_base + TPM_C0SC);
}
static inline void tpm_timer_enable(void)
{
unsigned int val;
/* channel enabled in sw compare mode */
val = readl(timer_base + TPM_C0SC);
val |= (TPM_C0SC_MODE_SW_COMPARE << TPM_C0SC_MODE_SHIFT) |
TPM_C0SC_CHIE;
writel(val, timer_base + TPM_C0SC);
}
static inline void tpm_irq_acknowledge(void)
{
writel(TPM_STATUS_CH0F, timer_base + TPM_STATUS);
}
static struct delay_timer tpm_delay_timer;
static inline unsigned long tpm_read_counter(void)
{
return readl(timer_base + TPM_CNT);
}
static unsigned long tpm_read_current_timer(void)
{
return tpm_read_counter();
}
static u64 notrace tpm_read_sched_clock(void)
{
return tpm_read_counter();
}
static int __init tpm_clocksource_init(unsigned long rate)
{
tpm_delay_timer.read_current_timer = &tpm_read_current_timer;
tpm_delay_timer.freq = rate;
register_current_timer_delay(&tpm_delay_timer);
sched_clock_register(tpm_read_sched_clock, 32, rate);
return clocksource_mmio_init(timer_base + TPM_CNT, "imx-tpm",
rate, 200, 32, clocksource_mmio_readl_up);
}
static int tpm_set_next_event(unsigned long delta,
struct clock_event_device *evt)
{
unsigned long next, now;
next = tpm_read_counter();
next += delta;
writel(next, timer_base + TPM_C0V);
now = tpm_read_counter();
/*
* NOTE: We observed in a very small probability, the bus fabric
* contention between GPU and A7 may results a few cycles delay
* of writing CNT registers which may cause the min_delta event got
* missed, so we need add a ETIME check here in case it happened.
*/
return (int)((next - now) <= 0) ? -ETIME : 0;
}
static int tpm_set_state_oneshot(struct clock_event_device *evt)
{
tpm_timer_enable();
return 0;
}
static int tpm_set_state_shutdown(struct clock_event_device *evt)
{
tpm_timer_disable();
return 0;
}
static irqreturn_t tpm_timer_interrupt(int irq, void *dev_id)
{
struct clock_event_device *evt = dev_id;
tpm_irq_acknowledge();
evt->event_handler(evt);
return IRQ_HANDLED;
}
static struct clock_event_device clockevent_tpm = {
.name = "i.MX7ULP TPM Timer",
.features = CLOCK_EVT_FEAT_ONESHOT,
.set_state_oneshot = tpm_set_state_oneshot,
.set_next_event = tpm_set_next_event,
.set_state_shutdown = tpm_set_state_shutdown,
.rating = 200,
};
static int __init tpm_clockevent_init(unsigned long rate, int irq)
{
int ret;
ret = request_irq(irq, tpm_timer_interrupt, IRQF_TIMER | IRQF_IRQPOLL,
"i.MX7ULP TPM Timer", &clockevent_tpm);
clockevent_tpm.cpumask = cpumask_of(0);
clockevent_tpm.irq = irq;
clockevents_config_and_register(&clockevent_tpm,
rate, 300, 0xfffffffe);
return ret;
}
static int __init tpm_timer_init(struct device_node *np)
{
struct clk *ipg, *per;
int irq, ret;
u32 rate;
timer_base = of_iomap(np, 0);
if (!timer_base) {
pr_err("tpm: failed to get base address\n");
return -ENXIO;
}
irq = irq_of_parse_and_map(np, 0);
if (!irq) {
pr_err("tpm: failed to get irq\n");
ret = -ENOENT;
goto err_iomap;
}
ipg = of_clk_get_by_name(np, "ipg");
per = of_clk_get_by_name(np, "per");
if (IS_ERR(ipg) || IS_ERR(per)) {
pr_err("tpm: failed to get igp or per clk\n");
ret = -ENODEV;
goto err_clk_get;
}
/* enable clk before accessing registers */
ret = clk_prepare_enable(ipg);
if (ret) {
pr_err("tpm: ipg clock enable failed (%d)\n", ret);
goto err_clk_get;
}
ret = clk_prepare_enable(per);
if (ret) {
pr_err("tpm: per clock enable failed (%d)\n", ret);
goto err_per_clk_enable;
}
/*
* Initialize tpm module to a known state
* 1) Counter disabled
* 2) TPM counter operates in up counting mode
* 3) Timer Overflow Interrupt disabled
* 4) Channel0 disabled
* 5) DMA transfers disabled
*/
writel(0, timer_base + TPM_SC);
writel(0, timer_base + TPM_CNT);
writel(0, timer_base + TPM_C0SC);
/* increase per cnt, div 8 by default */
writel(TPM_SC_CMOD_INC_PER_CNT | TPM_SC_CMOD_DIV_DEFAULT,
timer_base + TPM_SC);
/* set MOD register to maximum for free running mode */
writel(0xffffffff, timer_base + TPM_MOD);
rate = clk_get_rate(per) >> 3;
ret = tpm_clocksource_init(rate);
if (ret)
goto err_per_clk_enable;
ret = tpm_clockevent_init(rate, irq);
if (ret)
goto err_per_clk_enable;
return 0;
err_per_clk_enable:
clk_disable_unprepare(ipg);
err_clk_get:
clk_put(per);
clk_put(ipg);
err_iomap:
iounmap(timer_base);
return ret;
}
TIMER_OF_DECLARE(imx7ulp, "fsl,imx7ulp-tpm", tpm_timer_init);