1 /*
2  * Copyright (C) 2016 Imagination Technologies
3  * Author: Paul Burton <paul.burton@mips.com>
4  *
5  * This program is free software; you can redistribute it and/or modify it
6  * under the terms of the GNU General Public License as published by the
7  * Free Software Foundation; either version 2 of the License, or (at your
8  * option) any later version.
9  */
10 
11 #include <generated/utsrelease.h>
12 #include <linux/kernel.h>
13 #include <linux/io.h>
14 #include <linux/mfd/syscon.h>
15 #include <linux/module.h>
16 #include <linux/of_address.h>
17 #include <linux/of_platform.h>
18 #include <linux/platform_device.h>
19 #include <linux/regmap.h>
20 #include <linux/slab.h>
21 #include <linux/sysfs.h>
22 
23 struct img_ascii_lcd_ctx;
24 
25 /**
26  * struct img_ascii_lcd_config - Configuration information about an LCD model
27  * @num_chars: the number of characters the LCD can display
28  * @external_regmap: true if registers are in a system controller, else false
29  * @update: function called to update the LCD
30  */
31 struct img_ascii_lcd_config {
32 	unsigned int num_chars;
33 	bool external_regmap;
34 	void (*update)(struct img_ascii_lcd_ctx *ctx);
35 };
36 
37 /**
38  * struct img_ascii_lcd_ctx - Private data structure
39  * @pdev: the ASCII LCD platform device
40  * @base: the base address of the LCD registers
41  * @regmap: the regmap through which LCD registers are accessed
42  * @offset: the offset within regmap to the start of the LCD registers
43  * @cfg: pointer to the LCD model configuration
44  * @message: the full message to display or scroll on the LCD
45  * @message_len: the length of the @message string
46  * @scroll_pos: index of the first character of @message currently displayed
47  * @scroll_rate: scroll interval in jiffies
48  * @timer: timer used to implement scrolling
49  * @curr: the string currently displayed on the LCD
50  */
51 struct img_ascii_lcd_ctx {
52 	struct platform_device *pdev;
53 	union {
54 		void __iomem *base;
55 		struct regmap *regmap;
56 	};
57 	u32 offset;
58 	const struct img_ascii_lcd_config *cfg;
59 	char *message;
60 	unsigned int message_len;
61 	unsigned int scroll_pos;
62 	unsigned int scroll_rate;
63 	struct timer_list timer;
64 	char curr[] __aligned(8);
65 };
66 
67 /*
68  * MIPS Boston development board
69  */
70 
71 static void boston_update(struct img_ascii_lcd_ctx *ctx)
72 {
73 	ulong val;
74 
75 #if BITS_PER_LONG == 64
76 	val = *((u64 *)&ctx->curr[0]);
77 	__raw_writeq(val, ctx->base);
78 #elif BITS_PER_LONG == 32
79 	val = *((u32 *)&ctx->curr[0]);
80 	__raw_writel(val, ctx->base);
81 	val = *((u32 *)&ctx->curr[4]);
82 	__raw_writel(val, ctx->base + 4);
83 #else
84 # error Not 32 or 64 bit
85 #endif
86 }
87 
88 static struct img_ascii_lcd_config boston_config = {
89 	.num_chars = 8,
90 	.update = boston_update,
91 };
92 
93 /*
94  * MIPS Malta development board
95  */
96 
97 static void malta_update(struct img_ascii_lcd_ctx *ctx)
98 {
99 	unsigned int i;
100 	int err = 0;
101 
102 	for (i = 0; i < ctx->cfg->num_chars; i++) {
103 		err = regmap_write(ctx->regmap,
104 				   ctx->offset + (i * 8), ctx->curr[i]);
105 		if (err)
106 			break;
107 	}
108 
109 	if (unlikely(err))
110 		pr_err_ratelimited("Failed to update LCD display: %d\n", err);
111 }
112 
113 static struct img_ascii_lcd_config malta_config = {
114 	.num_chars = 8,
115 	.external_regmap = true,
116 	.update = malta_update,
117 };
118 
119 /*
120  * MIPS SEAD3 development board
121  */
122 
123 enum {
124 	SEAD3_REG_LCD_CTRL		= 0x00,
125 #define SEAD3_REG_LCD_CTRL_SETDRAM	BIT(7)
126 	SEAD3_REG_LCD_DATA		= 0x08,
127 	SEAD3_REG_CPLD_STATUS		= 0x10,
128 #define SEAD3_REG_CPLD_STATUS_BUSY	BIT(0)
129 	SEAD3_REG_CPLD_DATA		= 0x18,
130 #define SEAD3_REG_CPLD_DATA_BUSY	BIT(7)
131 };
132 
133 static int sead3_wait_sm_idle(struct img_ascii_lcd_ctx *ctx)
134 {
135 	unsigned int status;
136 	int err;
137 
138 	do {
139 		err = regmap_read(ctx->regmap,
140 				  ctx->offset + SEAD3_REG_CPLD_STATUS,
141 				  &status);
142 		if (err)
143 			return err;
144 	} while (status & SEAD3_REG_CPLD_STATUS_BUSY);
145 
146 	return 0;
147 
148 }
149 
150 static int sead3_wait_lcd_idle(struct img_ascii_lcd_ctx *ctx)
151 {
152 	unsigned int cpld_data;
153 	int err;
154 
155 	err = sead3_wait_sm_idle(ctx);
156 	if (err)
157 		return err;
158 
159 	do {
160 		err = regmap_read(ctx->regmap,
161 				  ctx->offset + SEAD3_REG_LCD_CTRL,
162 				  &cpld_data);
163 		if (err)
164 			return err;
165 
166 		err = sead3_wait_sm_idle(ctx);
167 		if (err)
168 			return err;
169 
170 		err = regmap_read(ctx->regmap,
171 				  ctx->offset + SEAD3_REG_CPLD_DATA,
172 				  &cpld_data);
173 		if (err)
174 			return err;
175 	} while (cpld_data & SEAD3_REG_CPLD_DATA_BUSY);
176 
177 	return 0;
178 }
179 
180 static void sead3_update(struct img_ascii_lcd_ctx *ctx)
181 {
182 	unsigned int i;
183 	int err = 0;
184 
185 	for (i = 0; i < ctx->cfg->num_chars; i++) {
186 		err = sead3_wait_lcd_idle(ctx);
187 		if (err)
188 			break;
189 
190 		err = regmap_write(ctx->regmap,
191 				   ctx->offset + SEAD3_REG_LCD_CTRL,
192 				   SEAD3_REG_LCD_CTRL_SETDRAM | i);
193 		if (err)
194 			break;
195 
196 		err = sead3_wait_lcd_idle(ctx);
197 		if (err)
198 			break;
199 
200 		err = regmap_write(ctx->regmap,
201 				   ctx->offset + SEAD3_REG_LCD_DATA,
202 				   ctx->curr[i]);
203 		if (err)
204 			break;
205 	}
206 
207 	if (unlikely(err))
208 		pr_err_ratelimited("Failed to update LCD display: %d\n", err);
209 }
210 
211 static struct img_ascii_lcd_config sead3_config = {
212 	.num_chars = 16,
213 	.external_regmap = true,
214 	.update = sead3_update,
215 };
216 
217 static const struct of_device_id img_ascii_lcd_matches[] = {
218 	{ .compatible = "img,boston-lcd", .data = &boston_config },
219 	{ .compatible = "mti,malta-lcd", .data = &malta_config },
220 	{ .compatible = "mti,sead3-lcd", .data = &sead3_config },
221 	{ /* sentinel */ }
222 };
223 MODULE_DEVICE_TABLE(of, img_ascii_lcd_matches);
224 
225 /**
226  * img_ascii_lcd_scroll() - scroll the display by a character
227  * @t: really a pointer to the private data structure
228  *
229  * Scroll the current message along the LCD by one character, rearming the
230  * timer if required.
231  */
232 static void img_ascii_lcd_scroll(struct timer_list *t)
233 {
234 	struct img_ascii_lcd_ctx *ctx = from_timer(ctx, t, timer);
235 	unsigned int i, ch = ctx->scroll_pos;
236 	unsigned int num_chars = ctx->cfg->num_chars;
237 
238 	/* update the current message string */
239 	for (i = 0; i < num_chars;) {
240 		/* copy as many characters from the string as possible */
241 		for (; i < num_chars && ch < ctx->message_len; i++, ch++)
242 			ctx->curr[i] = ctx->message[ch];
243 
244 		/* wrap around to the start of the string */
245 		ch = 0;
246 	}
247 
248 	/* update the LCD */
249 	ctx->cfg->update(ctx);
250 
251 	/* move on to the next character */
252 	ctx->scroll_pos++;
253 	ctx->scroll_pos %= ctx->message_len;
254 
255 	/* rearm the timer */
256 	if (ctx->message_len > ctx->cfg->num_chars)
257 		mod_timer(&ctx->timer, jiffies + ctx->scroll_rate);
258 }
259 
260 /**
261  * img_ascii_lcd_display() - set the message to be displayed
262  * @ctx: pointer to the private data structure
263  * @msg: the message to display
264  * @count: length of msg, or -1
265  *
266  * Display a new message @msg on the LCD. @msg can be longer than the number of
267  * characters the LCD can display, in which case it will begin scrolling across
268  * the LCD display.
269  *
270  * Return: 0 on success, -ENOMEM on memory allocation failure
271  */
272 static int img_ascii_lcd_display(struct img_ascii_lcd_ctx *ctx,
273 			     const char *msg, ssize_t count)
274 {
275 	char *new_msg;
276 
277 	/* stop the scroll timer */
278 	del_timer_sync(&ctx->timer);
279 
280 	if (count == -1)
281 		count = strlen(msg);
282 
283 	/* if the string ends with a newline, trim it */
284 	if (msg[count - 1] == '\n')
285 		count--;
286 
287 	new_msg = devm_kmalloc(&ctx->pdev->dev, count + 1, GFP_KERNEL);
288 	if (!new_msg)
289 		return -ENOMEM;
290 
291 	memcpy(new_msg, msg, count);
292 	new_msg[count] = 0;
293 
294 	if (ctx->message)
295 		devm_kfree(&ctx->pdev->dev, ctx->message);
296 
297 	ctx->message = new_msg;
298 	ctx->message_len = count;
299 	ctx->scroll_pos = 0;
300 
301 	/* update the LCD */
302 	img_ascii_lcd_scroll(&ctx->timer);
303 
304 	return 0;
305 }
306 
307 /**
308  * message_show() - read message via sysfs
309  * @dev: the LCD device
310  * @attr: the LCD message attribute
311  * @buf: the buffer to read the message into
312  *
313  * Read the current message being displayed or scrolled across the LCD display
314  * into @buf, for reads from sysfs.
315  *
316  * Return: the number of characters written to @buf
317  */
318 static ssize_t message_show(struct device *dev, struct device_attribute *attr,
319 			    char *buf)
320 {
321 	struct img_ascii_lcd_ctx *ctx = dev_get_drvdata(dev);
322 
323 	return sprintf(buf, "%s\n", ctx->message);
324 }
325 
326 /**
327  * message_store() - write a new message via sysfs
328  * @dev: the LCD device
329  * @attr: the LCD message attribute
330  * @buf: the buffer containing the new message
331  * @count: the size of the message in @buf
332  *
333  * Write a new message to display or scroll across the LCD display from sysfs.
334  *
335  * Return: the size of the message on success, else -ERRNO
336  */
337 static ssize_t message_store(struct device *dev, struct device_attribute *attr,
338 			     const char *buf, size_t count)
339 {
340 	struct img_ascii_lcd_ctx *ctx = dev_get_drvdata(dev);
341 	int err;
342 
343 	err = img_ascii_lcd_display(ctx, buf, count);
344 	return err ?: count;
345 }
346 
347 static DEVICE_ATTR_RW(message);
348 
349 /**
350  * img_ascii_lcd_probe() - probe an LCD display device
351  * @pdev: the LCD platform device
352  *
353  * Probe an LCD display device, ensuring that we have the required resources in
354  * order to access the LCD & setting up private data as well as sysfs files.
355  *
356  * Return: 0 on success, else -ERRNO
357  */
358 static int img_ascii_lcd_probe(struct platform_device *pdev)
359 {
360 	const struct of_device_id *match;
361 	const struct img_ascii_lcd_config *cfg;
362 	struct img_ascii_lcd_ctx *ctx;
363 	struct resource *res;
364 	int err;
365 
366 	match = of_match_device(img_ascii_lcd_matches, &pdev->dev);
367 	if (!match)
368 		return -ENODEV;
369 
370 	cfg = match->data;
371 	ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx) + cfg->num_chars,
372 			   GFP_KERNEL);
373 	if (!ctx)
374 		return -ENOMEM;
375 
376 	if (cfg->external_regmap) {
377 		ctx->regmap = syscon_node_to_regmap(pdev->dev.parent->of_node);
378 		if (IS_ERR(ctx->regmap))
379 			return PTR_ERR(ctx->regmap);
380 
381 		if (of_property_read_u32(pdev->dev.of_node, "offset",
382 					 &ctx->offset))
383 			return -EINVAL;
384 	} else {
385 		res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
386 		ctx->base = devm_ioremap_resource(&pdev->dev, res);
387 		if (IS_ERR(ctx->base))
388 			return PTR_ERR(ctx->base);
389 	}
390 
391 	ctx->pdev = pdev;
392 	ctx->cfg = cfg;
393 	ctx->message = NULL;
394 	ctx->scroll_pos = 0;
395 	ctx->scroll_rate = HZ / 2;
396 
397 	/* initialise a timer for scrolling the message */
398 	timer_setup(&ctx->timer, img_ascii_lcd_scroll, 0);
399 
400 	platform_set_drvdata(pdev, ctx);
401 
402 	/* display a default message */
403 	err = img_ascii_lcd_display(ctx, "Linux " UTS_RELEASE "       ", -1);
404 	if (err)
405 		goto out_del_timer;
406 
407 	err = device_create_file(&pdev->dev, &dev_attr_message);
408 	if (err)
409 		goto out_del_timer;
410 
411 	return 0;
412 out_del_timer:
413 	del_timer_sync(&ctx->timer);
414 	return err;
415 }
416 
417 /**
418  * img_ascii_lcd_remove() - remove an LCD display device
419  * @pdev: the LCD platform device
420  *
421  * Remove an LCD display device, freeing private resources & ensuring that the
422  * driver stops using the LCD display registers.
423  *
424  * Return: 0
425  */
426 static int img_ascii_lcd_remove(struct platform_device *pdev)
427 {
428 	struct img_ascii_lcd_ctx *ctx = platform_get_drvdata(pdev);
429 
430 	device_remove_file(&pdev->dev, &dev_attr_message);
431 	del_timer_sync(&ctx->timer);
432 	return 0;
433 }
434 
435 static struct platform_driver img_ascii_lcd_driver = {
436 	.driver = {
437 		.name		= "img-ascii-lcd",
438 		.of_match_table	= img_ascii_lcd_matches,
439 	},
440 	.probe	= img_ascii_lcd_probe,
441 	.remove	= img_ascii_lcd_remove,
442 };
443 module_platform_driver(img_ascii_lcd_driver);
444 
445 MODULE_DESCRIPTION("Imagination Technologies ASCII LCD Display");
446 MODULE_AUTHOR("Paul Burton <paul.burton@mips.com>");
447 MODULE_LICENSE("GPL");
448