linux/drivers/auxdisplay/img-ascii-lcd.c

448 lines
11 KiB
C

/*
* Copyright (C) 2016 Imagination Technologies
* Author: Paul Burton <paul.burton@mips.com>
*
* 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 <generated/utsrelease.h>
#include <linux/kernel.h>
#include <linux/io.h>
#include <linux/mfd/syscon.h>
#include <linux/module.h>
#include <linux/of_address.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/slab.h>
#include <linux/sysfs.h>
struct img_ascii_lcd_ctx;
/**
* struct img_ascii_lcd_config - Configuration information about an LCD model
* @num_chars: the number of characters the LCD can display
* @external_regmap: true if registers are in a system controller, else false
* @update: function called to update the LCD
*/
struct img_ascii_lcd_config {
unsigned int num_chars;
bool external_regmap;
void (*update)(struct img_ascii_lcd_ctx *ctx);
};
/**
* struct img_ascii_lcd_ctx - Private data structure
* @pdev: the ASCII LCD platform device
* @base: the base address of the LCD registers
* @regmap: the regmap through which LCD registers are accessed
* @offset: the offset within regmap to the start of the LCD registers
* @cfg: pointer to the LCD model configuration
* @message: the full message to display or scroll on the LCD
* @message_len: the length of the @message string
* @scroll_pos: index of the first character of @message currently displayed
* @scroll_rate: scroll interval in jiffies
* @timer: timer used to implement scrolling
* @curr: the string currently displayed on the LCD
*/
struct img_ascii_lcd_ctx {
struct platform_device *pdev;
union {
void __iomem *base;
struct regmap *regmap;
};
u32 offset;
const struct img_ascii_lcd_config *cfg;
char *message;
unsigned int message_len;
unsigned int scroll_pos;
unsigned int scroll_rate;
struct timer_list timer;
char curr[] __aligned(8);
};
/*
* MIPS Boston development board
*/
static void boston_update(struct img_ascii_lcd_ctx *ctx)
{
ulong val;
#if BITS_PER_LONG == 64
val = *((u64 *)&ctx->curr[0]);
__raw_writeq(val, ctx->base);
#elif BITS_PER_LONG == 32
val = *((u32 *)&ctx->curr[0]);
__raw_writel(val, ctx->base);
val = *((u32 *)&ctx->curr[4]);
__raw_writel(val, ctx->base + 4);
#else
# error Not 32 or 64 bit
#endif
}
static struct img_ascii_lcd_config boston_config = {
.num_chars = 8,
.update = boston_update,
};
/*
* MIPS Malta development board
*/
static void malta_update(struct img_ascii_lcd_ctx *ctx)
{
unsigned int i;
int err;
for (i = 0; i < ctx->cfg->num_chars; i++) {
err = regmap_write(ctx->regmap,
ctx->offset + (i * 8), ctx->curr[i]);
if (err)
break;
}
if (unlikely(err))
pr_err_ratelimited("Failed to update LCD display: %d\n", err);
}
static struct img_ascii_lcd_config malta_config = {
.num_chars = 8,
.external_regmap = true,
.update = malta_update,
};
/*
* MIPS SEAD3 development board
*/
enum {
SEAD3_REG_LCD_CTRL = 0x00,
#define SEAD3_REG_LCD_CTRL_SETDRAM BIT(7)
SEAD3_REG_LCD_DATA = 0x08,
SEAD3_REG_CPLD_STATUS = 0x10,
#define SEAD3_REG_CPLD_STATUS_BUSY BIT(0)
SEAD3_REG_CPLD_DATA = 0x18,
#define SEAD3_REG_CPLD_DATA_BUSY BIT(7)
};
static int sead3_wait_sm_idle(struct img_ascii_lcd_ctx *ctx)
{
unsigned int status;
int err;
do {
err = regmap_read(ctx->regmap,
ctx->offset + SEAD3_REG_CPLD_STATUS,
&status);
if (err)
return err;
} while (status & SEAD3_REG_CPLD_STATUS_BUSY);
return 0;
}
static int sead3_wait_lcd_idle(struct img_ascii_lcd_ctx *ctx)
{
unsigned int cpld_data;
int err;
err = sead3_wait_sm_idle(ctx);
if (err)
return err;
do {
err = regmap_read(ctx->regmap,
ctx->offset + SEAD3_REG_LCD_CTRL,
&cpld_data);
if (err)
return err;
err = sead3_wait_sm_idle(ctx);
if (err)
return err;
err = regmap_read(ctx->regmap,
ctx->offset + SEAD3_REG_CPLD_DATA,
&cpld_data);
if (err)
return err;
} while (cpld_data & SEAD3_REG_CPLD_DATA_BUSY);
return 0;
}
static void sead3_update(struct img_ascii_lcd_ctx *ctx)
{
unsigned int i;
int err;
for (i = 0; i < ctx->cfg->num_chars; i++) {
err = sead3_wait_lcd_idle(ctx);
if (err)
break;
err = regmap_write(ctx->regmap,
ctx->offset + SEAD3_REG_LCD_CTRL,
SEAD3_REG_LCD_CTRL_SETDRAM | i);
if (err)
break;
err = sead3_wait_lcd_idle(ctx);
if (err)
break;
err = regmap_write(ctx->regmap,
ctx->offset + SEAD3_REG_LCD_DATA,
ctx->curr[i]);
if (err)
break;
}
if (unlikely(err))
pr_err_ratelimited("Failed to update LCD display: %d\n", err);
}
static struct img_ascii_lcd_config sead3_config = {
.num_chars = 16,
.external_regmap = true,
.update = sead3_update,
};
static const struct of_device_id img_ascii_lcd_matches[] = {
{ .compatible = "img,boston-lcd", .data = &boston_config },
{ .compatible = "mti,malta-lcd", .data = &malta_config },
{ .compatible = "mti,sead3-lcd", .data = &sead3_config },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, img_ascii_lcd_matches);
/**
* img_ascii_lcd_scroll() - scroll the display by a character
* @arg: really a pointer to the private data structure
*
* Scroll the current message along the LCD by one character, rearming the
* timer if required.
*/
static void img_ascii_lcd_scroll(struct timer_list *t)
{
struct img_ascii_lcd_ctx *ctx = from_timer(ctx, t, timer);
unsigned int i, ch = ctx->scroll_pos;
unsigned int num_chars = ctx->cfg->num_chars;
/* update the current message string */
for (i = 0; i < num_chars;) {
/* copy as many characters from the string as possible */
for (; i < num_chars && ch < ctx->message_len; i++, ch++)
ctx->curr[i] = ctx->message[ch];
/* wrap around to the start of the string */
ch = 0;
}
/* update the LCD */
ctx->cfg->update(ctx);
/* move on to the next character */
ctx->scroll_pos++;
ctx->scroll_pos %= ctx->message_len;
/* rearm the timer */
if (ctx->message_len > ctx->cfg->num_chars)
mod_timer(&ctx->timer, jiffies + ctx->scroll_rate);
}
/**
* img_ascii_lcd_display() - set the message to be displayed
* @ctx: pointer to the private data structure
* @msg: the message to display
* @count: length of msg, or -1
*
* Display a new message @msg on the LCD. @msg can be longer than the number of
* characters the LCD can display, in which case it will begin scrolling across
* the LCD display.
*
* Return: 0 on success, -ENOMEM on memory allocation failure
*/
static int img_ascii_lcd_display(struct img_ascii_lcd_ctx *ctx,
const char *msg, ssize_t count)
{
char *new_msg;
/* stop the scroll timer */
del_timer_sync(&ctx->timer);
if (count == -1)
count = strlen(msg);
/* if the string ends with a newline, trim it */
if (msg[count - 1] == '\n')
count--;
new_msg = devm_kmalloc(&ctx->pdev->dev, count + 1, GFP_KERNEL);
if (!new_msg)
return -ENOMEM;
memcpy(new_msg, msg, count);
new_msg[count] = 0;
if (ctx->message)
devm_kfree(&ctx->pdev->dev, ctx->message);
ctx->message = new_msg;
ctx->message_len = count;
ctx->scroll_pos = 0;
/* update the LCD */
img_ascii_lcd_scroll(&ctx->timer);
return 0;
}
/**
* message_show() - read message via sysfs
* @dev: the LCD device
* @attr: the LCD message attribute
* @buf: the buffer to read the message into
*
* Read the current message being displayed or scrolled across the LCD display
* into @buf, for reads from sysfs.
*
* Return: the number of characters written to @buf
*/
static ssize_t message_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
struct img_ascii_lcd_ctx *ctx = dev_get_drvdata(dev);
return sprintf(buf, "%s\n", ctx->message);
}
/**
* message_store() - write a new message via sysfs
* @dev: the LCD device
* @attr: the LCD message attribute
* @buf: the buffer containing the new message
* @count: the size of the message in @buf
*
* Write a new message to display or scroll across the LCD display from sysfs.
*
* Return: the size of the message on success, else -ERRNO
*/
static ssize_t message_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
struct img_ascii_lcd_ctx *ctx = dev_get_drvdata(dev);
int err;
err = img_ascii_lcd_display(ctx, buf, count);
return err ?: count;
}
static DEVICE_ATTR_RW(message);
/**
* img_ascii_lcd_probe() - probe an LCD display device
* @pdev: the LCD platform device
*
* Probe an LCD display device, ensuring that we have the required resources in
* order to access the LCD & setting up private data as well as sysfs files.
*
* Return: 0 on success, else -ERRNO
*/
static int img_ascii_lcd_probe(struct platform_device *pdev)
{
const struct of_device_id *match;
const struct img_ascii_lcd_config *cfg;
struct img_ascii_lcd_ctx *ctx;
struct resource *res;
int err;
match = of_match_device(img_ascii_lcd_matches, &pdev->dev);
if (!match)
return -ENODEV;
cfg = match->data;
ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx) + cfg->num_chars,
GFP_KERNEL);
if (!ctx)
return -ENOMEM;
if (cfg->external_regmap) {
ctx->regmap = syscon_node_to_regmap(pdev->dev.parent->of_node);
if (IS_ERR(ctx->regmap))
return PTR_ERR(ctx->regmap);
if (of_property_read_u32(pdev->dev.of_node, "offset",
&ctx->offset))
return -EINVAL;
} else {
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
ctx->base = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(ctx->base))
return PTR_ERR(ctx->base);
}
ctx->pdev = pdev;
ctx->cfg = cfg;
ctx->message = NULL;
ctx->scroll_pos = 0;
ctx->scroll_rate = HZ / 2;
/* initialise a timer for scrolling the message */
timer_setup(&ctx->timer, img_ascii_lcd_scroll, 0);
platform_set_drvdata(pdev, ctx);
/* display a default message */
err = img_ascii_lcd_display(ctx, "Linux " UTS_RELEASE " ", -1);
if (err)
goto out_del_timer;
err = device_create_file(&pdev->dev, &dev_attr_message);
if (err)
goto out_del_timer;
return 0;
out_del_timer:
del_timer_sync(&ctx->timer);
return err;
}
/**
* img_ascii_lcd_remove() - remove an LCD display device
* @pdev: the LCD platform device
*
* Remove an LCD display device, freeing private resources & ensuring that the
* driver stops using the LCD display registers.
*
* Return: 0
*/
static int img_ascii_lcd_remove(struct platform_device *pdev)
{
struct img_ascii_lcd_ctx *ctx = platform_get_drvdata(pdev);
device_remove_file(&pdev->dev, &dev_attr_message);
del_timer_sync(&ctx->timer);
return 0;
}
static struct platform_driver img_ascii_lcd_driver = {
.driver = {
.name = "img-ascii-lcd",
.of_match_table = img_ascii_lcd_matches,
},
.probe = img_ascii_lcd_probe,
.remove = img_ascii_lcd_remove,
};
module_platform_driver(img_ascii_lcd_driver);
MODULE_DESCRIPTION("Imagination Technologies ASCII LCD Display");
MODULE_AUTHOR("Paul Burton <paul.burton@mips.com>");
MODULE_LICENSE("GPL");