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1 /*
2  * Driver for the Solomon SSD1307 OLED controller
3  *
4  * Copyright 2012 Free Electrons
5  *
6  * Licensed under the GPLv2 or later.
7  */
8 
9 #include <linux/module.h>
10 #include <linux/kernel.h>
11 #include <linux/i2c.h>
12 #include <linux/fb.h>
13 #include <linux/uaccess.h>
14 #include <linux/of_device.h>
15 #include <linux/of_gpio.h>
16 #include <linux/pwm.h>
17 #include <linux/delay.h>
18 
19 #define SSD1307FB_WIDTH			96
20 #define SSD1307FB_HEIGHT		16
21 
22 #define SSD1307FB_DATA			0x40
23 #define SSD1307FB_COMMAND		0x80
24 
25 #define SSD1307FB_CONTRAST		0x81
26 #define SSD1307FB_SEG_REMAP_ON		0xa1
27 #define SSD1307FB_DISPLAY_OFF		0xae
28 #define SSD1307FB_DISPLAY_ON		0xaf
29 #define SSD1307FB_START_PAGE_ADDRESS	0xb0
30 
31 struct ssd1307fb_par {
32 	struct i2c_client *client;
33 	struct fb_info *info;
34 	struct pwm_device *pwm;
35 	u32 pwm_period;
36 	int reset;
37 };
38 
39 static struct fb_fix_screeninfo ssd1307fb_fix = {
40 	.id		= "Solomon SSD1307",
41 	.type		= FB_TYPE_PACKED_PIXELS,
42 	.visual		= FB_VISUAL_MONO10,
43 	.xpanstep	= 0,
44 	.ypanstep	= 0,
45 	.ywrapstep	= 0,
46 	.line_length	= SSD1307FB_WIDTH / 8,
47 	.accel		= FB_ACCEL_NONE,
48 };
49 
50 static struct fb_var_screeninfo ssd1307fb_var = {
51 	.xres		= SSD1307FB_WIDTH,
52 	.yres		= SSD1307FB_HEIGHT,
53 	.xres_virtual	= SSD1307FB_WIDTH,
54 	.yres_virtual	= SSD1307FB_HEIGHT,
55 	.bits_per_pixel	= 1,
56 };
57 
ssd1307fb_write_array(struct i2c_client * client,u8 type,u8 * cmd,u32 len)58 static int ssd1307fb_write_array(struct i2c_client *client, u8 type, u8 *cmd, u32 len)
59 {
60 	u8 *buf;
61 	int ret = 0;
62 
63 	buf = kzalloc(len + 1, GFP_KERNEL);
64 	if (!buf) {
65 		dev_err(&client->dev, "Couldn't allocate sending buffer.\n");
66 		return -ENOMEM;
67 	}
68 
69 	buf[0] = type;
70 	memcpy(buf + 1, cmd, len);
71 
72 	ret = i2c_master_send(client, buf, len + 1);
73 	if (ret != len + 1) {
74 		dev_err(&client->dev, "Couldn't send I2C command.\n");
75 		goto error;
76 	}
77 
78 error:
79 	kfree(buf);
80 	return ret;
81 }
82 
ssd1307fb_write_cmd_array(struct i2c_client * client,u8 * cmd,u32 len)83 static inline int ssd1307fb_write_cmd_array(struct i2c_client *client, u8 *cmd, u32 len)
84 {
85 	return ssd1307fb_write_array(client, SSD1307FB_COMMAND, cmd, len);
86 }
87 
ssd1307fb_write_cmd(struct i2c_client * client,u8 cmd)88 static inline int ssd1307fb_write_cmd(struct i2c_client *client, u8 cmd)
89 {
90 	return ssd1307fb_write_cmd_array(client, &cmd, 1);
91 }
92 
ssd1307fb_write_data_array(struct i2c_client * client,u8 * cmd,u32 len)93 static inline int ssd1307fb_write_data_array(struct i2c_client *client, u8 *cmd, u32 len)
94 {
95 	return ssd1307fb_write_array(client, SSD1307FB_DATA, cmd, len);
96 }
97 
ssd1307fb_write_data(struct i2c_client * client,u8 data)98 static inline int ssd1307fb_write_data(struct i2c_client *client, u8 data)
99 {
100 	return ssd1307fb_write_data_array(client, &data, 1);
101 }
102 
ssd1307fb_update_display(struct ssd1307fb_par * par)103 static void ssd1307fb_update_display(struct ssd1307fb_par *par)
104 {
105 	u8 *vmem = par->info->screen_base;
106 	int i, j, k;
107 
108 	/*
109 	 * The screen is divided in pages, each having a height of 8
110 	 * pixels, and the width of the screen. When sending a byte of
111 	 * data to the controller, it gives the 8 bits for the current
112 	 * column. I.e, the first byte are the 8 bits of the first
113 	 * column, then the 8 bits for the second column, etc.
114 	 *
115 	 *
116 	 * Representation of the screen, assuming it is 5 bits
117 	 * wide. Each letter-number combination is a bit that controls
118 	 * one pixel.
119 	 *
120 	 * A0 A1 A2 A3 A4
121 	 * B0 B1 B2 B3 B4
122 	 * C0 C1 C2 C3 C4
123 	 * D0 D1 D2 D3 D4
124 	 * E0 E1 E2 E3 E4
125 	 * F0 F1 F2 F3 F4
126 	 * G0 G1 G2 G3 G4
127 	 * H0 H1 H2 H3 H4
128 	 *
129 	 * If you want to update this screen, you need to send 5 bytes:
130 	 *  (1) A0 B0 C0 D0 E0 F0 G0 H0
131 	 *  (2) A1 B1 C1 D1 E1 F1 G1 H1
132 	 *  (3) A2 B2 C2 D2 E2 F2 G2 H2
133 	 *  (4) A3 B3 C3 D3 E3 F3 G3 H3
134 	 *  (5) A4 B4 C4 D4 E4 F4 G4 H4
135 	 */
136 
137 	for (i = 0; i < (SSD1307FB_HEIGHT / 8); i++) {
138 		ssd1307fb_write_cmd(par->client, SSD1307FB_START_PAGE_ADDRESS + (i + 1));
139 		ssd1307fb_write_cmd(par->client, 0x00);
140 		ssd1307fb_write_cmd(par->client, 0x10);
141 
142 		for (j = 0; j < SSD1307FB_WIDTH; j++) {
143 			u8 buf = 0;
144 			for (k = 0; k < 8; k++) {
145 				u32 page_length = SSD1307FB_WIDTH * i;
146 				u32 index = page_length + (SSD1307FB_WIDTH * k + j) / 8;
147 				u8 byte = *(vmem + index);
148 				u8 bit = byte & (1 << (j % 8));
149 				bit = bit >> (j % 8);
150 				buf |= bit << k;
151 			}
152 			ssd1307fb_write_data(par->client, buf);
153 		}
154 	}
155 }
156 
157 
ssd1307fb_write(struct fb_info * info,const char __user * buf,size_t count,loff_t * ppos)158 static ssize_t ssd1307fb_write(struct fb_info *info, const char __user *buf,
159 		size_t count, loff_t *ppos)
160 {
161 	struct ssd1307fb_par *par = info->par;
162 	unsigned long total_size;
163 	unsigned long p = *ppos;
164 	u8 __iomem *dst;
165 
166 	total_size = info->fix.smem_len;
167 
168 	if (p > total_size)
169 		return -EINVAL;
170 
171 	if (count + p > total_size)
172 		count = total_size - p;
173 
174 	if (!count)
175 		return -EINVAL;
176 
177 	dst = (void __force *) (info->screen_base + p);
178 
179 	if (copy_from_user(dst, buf, count))
180 		return -EFAULT;
181 
182 	ssd1307fb_update_display(par);
183 
184 	*ppos += count;
185 
186 	return count;
187 }
188 
ssd1307fb_fillrect(struct fb_info * info,const struct fb_fillrect * rect)189 static void ssd1307fb_fillrect(struct fb_info *info, const struct fb_fillrect *rect)
190 {
191 	struct ssd1307fb_par *par = info->par;
192 	sys_fillrect(info, rect);
193 	ssd1307fb_update_display(par);
194 }
195 
ssd1307fb_copyarea(struct fb_info * info,const struct fb_copyarea * area)196 static void ssd1307fb_copyarea(struct fb_info *info, const struct fb_copyarea *area)
197 {
198 	struct ssd1307fb_par *par = info->par;
199 	sys_copyarea(info, area);
200 	ssd1307fb_update_display(par);
201 }
202 
ssd1307fb_imageblit(struct fb_info * info,const struct fb_image * image)203 static void ssd1307fb_imageblit(struct fb_info *info, const struct fb_image *image)
204 {
205 	struct ssd1307fb_par *par = info->par;
206 	sys_imageblit(info, image);
207 	ssd1307fb_update_display(par);
208 }
209 
210 static struct fb_ops ssd1307fb_ops = {
211 	.owner		= THIS_MODULE,
212 	.fb_read	= fb_sys_read,
213 	.fb_write	= ssd1307fb_write,
214 	.fb_fillrect	= ssd1307fb_fillrect,
215 	.fb_copyarea	= ssd1307fb_copyarea,
216 	.fb_imageblit	= ssd1307fb_imageblit,
217 };
218 
ssd1307fb_deferred_io(struct fb_info * info,struct list_head * pagelist)219 static void ssd1307fb_deferred_io(struct fb_info *info,
220 				struct list_head *pagelist)
221 {
222 	ssd1307fb_update_display(info->par);
223 }
224 
225 static struct fb_deferred_io ssd1307fb_defio = {
226 	.delay		= HZ,
227 	.deferred_io	= ssd1307fb_deferred_io,
228 };
229 
ssd1307fb_probe(struct i2c_client * client,const struct i2c_device_id * id)230 static int ssd1307fb_probe(struct i2c_client *client,
231 			   const struct i2c_device_id *id)
232 {
233 	struct fb_info *info;
234 	u32 vmem_size = SSD1307FB_WIDTH * SSD1307FB_HEIGHT / 8;
235 	struct ssd1307fb_par *par;
236 	u8 *vmem;
237 	int ret;
238 
239 	if (!client->dev.of_node) {
240 		dev_err(&client->dev, "No device tree data found!\n");
241 		return -EINVAL;
242 	}
243 
244 	info = framebuffer_alloc(sizeof(struct ssd1307fb_par), &client->dev);
245 	if (!info) {
246 		dev_err(&client->dev, "Couldn't allocate framebuffer.\n");
247 		return -ENOMEM;
248 	}
249 
250 	vmem = devm_kzalloc(&client->dev, vmem_size, GFP_KERNEL);
251 	if (!vmem) {
252 		dev_err(&client->dev, "Couldn't allocate graphical memory.\n");
253 		ret = -ENOMEM;
254 		goto fb_alloc_error;
255 	}
256 
257 	info->fbops = &ssd1307fb_ops;
258 	info->fix = ssd1307fb_fix;
259 	info->fbdefio = &ssd1307fb_defio;
260 
261 	info->var = ssd1307fb_var;
262 	info->var.red.length = 1;
263 	info->var.red.offset = 0;
264 	info->var.green.length = 1;
265 	info->var.green.offset = 0;
266 	info->var.blue.length = 1;
267 	info->var.blue.offset = 0;
268 
269 	info->screen_base = (u8 __force __iomem *)vmem;
270 	info->fix.smem_start = (unsigned long)vmem;
271 	info->fix.smem_len = vmem_size;
272 
273 	fb_deferred_io_init(info);
274 
275 	par = info->par;
276 	par->info = info;
277 	par->client = client;
278 
279 	par->reset = of_get_named_gpio(client->dev.of_node,
280 					 "reset-gpios", 0);
281 	if (!gpio_is_valid(par->reset)) {
282 		ret = -EINVAL;
283 		goto reset_oled_error;
284 	}
285 
286 	ret = devm_gpio_request_one(&client->dev, par->reset,
287 				    GPIOF_OUT_INIT_HIGH,
288 				    "oled-reset");
289 	if (ret) {
290 		dev_err(&client->dev,
291 			"failed to request gpio %d: %d\n",
292 			par->reset, ret);
293 		goto reset_oled_error;
294 	}
295 
296 	par->pwm = pwm_get(&client->dev, NULL);
297 	if (IS_ERR(par->pwm)) {
298 		dev_err(&client->dev, "Could not get PWM from device tree!\n");
299 		ret = PTR_ERR(par->pwm);
300 		goto pwm_error;
301 	}
302 
303 	par->pwm_period = pwm_get_period(par->pwm);
304 
305 	dev_dbg(&client->dev, "Using PWM%d with a %dns period.\n", par->pwm->pwm, par->pwm_period);
306 
307 	ret = register_framebuffer(info);
308 	if (ret) {
309 		dev_err(&client->dev, "Couldn't register the framebuffer\n");
310 		goto fbreg_error;
311 	}
312 
313 	i2c_set_clientdata(client, info);
314 
315 	/* Reset the screen */
316 	gpio_set_value(par->reset, 0);
317 	udelay(4);
318 	gpio_set_value(par->reset, 1);
319 	udelay(4);
320 
321 	/* Enable the PWM */
322 	pwm_config(par->pwm, par->pwm_period / 2, par->pwm_period);
323 	pwm_enable(par->pwm);
324 
325 	/* Map column 127 of the OLED to segment 0 */
326 	ret = ssd1307fb_write_cmd(client, SSD1307FB_SEG_REMAP_ON);
327 	if (ret < 0) {
328 		dev_err(&client->dev, "Couldn't remap the screen.\n");
329 		goto remap_error;
330 	}
331 
332 	/* Turn on the display */
333 	ret = ssd1307fb_write_cmd(client, SSD1307FB_DISPLAY_ON);
334 	if (ret < 0) {
335 		dev_err(&client->dev, "Couldn't turn the display on.\n");
336 		goto remap_error;
337 	}
338 
339 	dev_info(&client->dev, "fb%d: %s framebuffer device registered, using %d bytes of video memory\n", info->node, info->fix.id, vmem_size);
340 
341 	return 0;
342 
343 remap_error:
344 	unregister_framebuffer(info);
345 	pwm_disable(par->pwm);
346 fbreg_error:
347 	pwm_put(par->pwm);
348 pwm_error:
349 reset_oled_error:
350 	fb_deferred_io_cleanup(info);
351 fb_alloc_error:
352 	framebuffer_release(info);
353 	return ret;
354 }
355 
ssd1307fb_remove(struct i2c_client * client)356 static int ssd1307fb_remove(struct i2c_client *client)
357 {
358 	struct fb_info *info = i2c_get_clientdata(client);
359 	struct ssd1307fb_par *par = info->par;
360 
361 	unregister_framebuffer(info);
362 	pwm_disable(par->pwm);
363 	pwm_put(par->pwm);
364 	fb_deferred_io_cleanup(info);
365 	framebuffer_release(info);
366 
367 	return 0;
368 }
369 
370 static const struct i2c_device_id ssd1307fb_i2c_id[] = {
371 	{ "ssd1307fb", 0 },
372 	{ }
373 };
374 MODULE_DEVICE_TABLE(i2c, ssd1307fb_i2c_id);
375 
376 static const struct of_device_id ssd1307fb_of_match[] = {
377 	{ .compatible = "solomon,ssd1307fb-i2c" },
378 	{},
379 };
380 MODULE_DEVICE_TABLE(of, ssd1307fb_of_match);
381 
382 static struct i2c_driver ssd1307fb_driver = {
383 	.probe = ssd1307fb_probe,
384 	.remove = ssd1307fb_remove,
385 	.id_table = ssd1307fb_i2c_id,
386 	.driver = {
387 		.name = "ssd1307fb",
388 		.of_match_table = of_match_ptr(ssd1307fb_of_match),
389 		.owner = THIS_MODULE,
390 	},
391 };
392 
393 module_i2c_driver(ssd1307fb_driver);
394 
395 MODULE_DESCRIPTION("FB driver for the Solomon SSD1307 OLED controller");
396 MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>");
397 MODULE_LICENSE("GPL");
398