1 files changed, 457 insertions, 0 deletions
diff --git a/drivers/auxdisplay/img-ascii-lcd.c b/drivers/auxdisplay/img-ascii-lcd.c
new file mode 100644
index 000000000..c4bc6723a
--- /dev/null
+++ b/drivers/auxdisplay/img-ascii-lcd.c
@@ -0,0 +1,457 @@
+/*
+ * 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 = 0;
+
+	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 = 0;
+
+	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
+ * @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)
+{
+	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--;
+
+	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);
+
+	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");