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auxdisplay: Extract character line display core support
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Extract the character line display core support from the simple ASCII
LCD driver for the MIPS Boston, Malta & SEAD3 development boards into
its own subdriver, so it can be reused for other displays.

As this moves the "message" device attribute in sysfs in a "linedisp.N"
subdirectory, a symlink is added to preserve backwards compatibility.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
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@geertu @intel-lab-lkp
geertu authored and intel-lab-lkp committed Jun 25, 2021
1 parent 2c4ee5f commit 5505aed
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Showing 5 changed files with 320 additions and 167 deletions.
7 changes: 7 additions & 0 deletions drivers/auxdisplay/Kconfig
View file
Expand Up @@ -25,6 +25,12 @@ config CHARLCD
This is some character LCD core interface that multiple drivers can
use.

config LINEDISP
tristate "Character line display core support" if COMPILE_TEST
help
This is the core support for single-line character displays, to be
selected by drivers that use it.

config HD44780_COMMON
tristate "Common functions for HD44780 (and compatibles) LCD displays" if COMPILE_TEST
select CHARLCD
Expand Down Expand Up @@ -155,6 +161,7 @@ config IMG_ASCII_LCD
depends on HAS_IOMEM
default y if MIPS_MALTA
select MFD_SYSCON
select LINEDISP
help
Enable this to support the simple ASCII LCD displays found on
development boards such as the MIPS Boston, MIPS Malta & MIPS SEAD3
Expand Down
1 change: 1 addition & 0 deletions drivers/auxdisplay/Makefile
View file
Expand Up @@ -13,3 +13,4 @@ obj-$(CONFIG_HD44780) += hd44780.o
obj-$(CONFIG_HT16K33) += ht16k33.o
obj-$(CONFIG_PARPORT_PANEL) += panel.o
obj-$(CONFIG_LCD2S) += lcd2s.o
obj-$(CONFIG_LINEDISP) += line-display.o
205 changes: 38 additions & 167 deletions drivers/auxdisplay/img-ascii-lcd.c
View file
Expand Up @@ -4,7 +4,6 @@
* Author: Paul Burton <paul.burton@mips.com>
*/

#include <generated/utsrelease.h>
#include <linux/kernel.h>
#include <linux/io.h>
#include <linux/mfd/syscon.h>
Expand All @@ -14,7 +13,8 @@
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/slab.h>
#include <linux/sysfs.h>

#include "line-display.h"

struct img_ascii_lcd_ctx;

Expand All @@ -27,45 +27,37 @@ struct img_ascii_lcd_ctx;
struct img_ascii_lcd_config {
unsigned int num_chars;
bool external_regmap;
void (*update)(struct img_ascii_lcd_ctx *ctx);
void (*update)(struct linedisp *linedisp);
};

/**
* 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
* @linedisp: line display structure
* @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;
struct linedisp linedisp;
char curr[] __aligned(8);
};

/*
* MIPS Boston development board
*/

static void boston_update(struct img_ascii_lcd_ctx *ctx)
static void boston_update(struct linedisp *linedisp)
{
struct img_ascii_lcd_ctx *ctx =
container_of(linedisp, struct img_ascii_lcd_ctx, linedisp);
ulong val;

#if BITS_PER_LONG == 64
Expand All @@ -90,12 +82,14 @@ static struct img_ascii_lcd_config boston_config = {
* MIPS Malta development board
*/

static void malta_update(struct img_ascii_lcd_ctx *ctx)
static void malta_update(struct linedisp *linedisp)
{
struct img_ascii_lcd_ctx *ctx =
container_of(linedisp, struct img_ascii_lcd_ctx, linedisp);
unsigned int i;
int err = 0;

for (i = 0; i < ctx->cfg->num_chars; i++) {
for (i = 0; i < linedisp->num_chars; i++) {
err = regmap_write(ctx->regmap,
ctx->offset + (i * 8), ctx->curr[i]);
if (err)
Expand Down Expand Up @@ -173,12 +167,14 @@ static int sead3_wait_lcd_idle(struct img_ascii_lcd_ctx *ctx)
return 0;
}

static void sead3_update(struct img_ascii_lcd_ctx *ctx)
static void sead3_update(struct linedisp *linedisp)
{
struct img_ascii_lcd_ctx *ctx =
container_of(linedisp, struct img_ascii_lcd_ctx, linedisp);
unsigned int i;
int err = 0;

for (i = 0; i < ctx->cfg->num_chars; i++) {
for (i = 0; i < linedisp->num_chars; i++) {
err = sead3_wait_lcd_idle(ctx);
if (err)
break;
Expand Down Expand Up @@ -218,140 +214,22 @@ static const struct of_device_id img_ascii_lcd_matches[] = {
};
MODULE_DEVICE_TABLE(of, img_ascii_lcd_matches);

/**
* img_ascii_lcd_scroll() - scroll the display by a character
* @t: 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)
static int sysfs_create_file_link(struct kobject *parent,
struct kobject *target, const char *name)
{
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);
struct kernfs_node *kn;

/* move on to the next character */
ctx->scroll_pos++;
ctx->scroll_pos %= ctx->message_len;
kn = kernfs_find_and_get(target->sd, "message");
if (!kn)
return -ENOENT;

/* 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--;

if (!count) {
/* clear the LCD */
devm_kfree(&ctx->pdev->dev, ctx->message);
ctx->message = NULL;
ctx->message_len = 0;
memset(ctx->curr, ' ', ctx->cfg->num_chars);
ctx->cfg->update(ctx);
return 0;
}

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);
kn = kernfs_create_link(parent->sd, "message", kn);
if (!kn)
return -ENOENT;

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 sysfs_emit(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
Expand Down Expand Up @@ -391,29 +269,22 @@ static int img_ascii_lcd_probe(struct platform_device *pdev)
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);
err = linedisp_register(&ctx->linedisp, dev, cfg->num_chars, ctx->curr,
cfg->update);
if (err)
goto out_del_timer;
return err;

err = device_create_file(dev, &dev_attr_message);
/* for backwards compatibility */
err = sysfs_create_file_link(&dev->kobj, &ctx->linedisp.dev.kobj,
"message");
if (err)
goto out_del_timer;
goto err_unregister;

platform_set_drvdata(pdev, ctx);
return 0;
out_del_timer:
del_timer_sync(&ctx->timer);

err_unregister:
linedisp_unregister(&ctx->linedisp);
return err;
}

Expand All @@ -430,8 +301,8 @@ 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);
sysfs_remove_link(&pdev->dev.kobj, "message");
linedisp_unregister(&ctx->linedisp);
return 0;
}

Expand Down

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