blob: fe8616a8d28748fc6b952d7c3664fb20c6eb1f71 [file] [log] [blame]
Linus Walleijce896242010-07-17 12:33:48 +01001/*
2 * Driver for the on-board character LCD found on some ARM reference boards
3 * This is basically an Hitachi HD44780 LCD with a custom IP block to drive it
4 * http://en.wikipedia.org/wiki/HD44780_Character_LCD
5 * Currently it will just display the text "ARM Linux" and the linux version
6 *
7 * License terms: GNU General Public License (GPL) version 2
8 * Author: Linus Walleij <triad@df.lth.se>
9 */
10#include <linux/init.h>
11#include <linux/module.h>
12#include <linux/interrupt.h>
13#include <linux/platform_device.h>
14#include <linux/completion.h>
15#include <linux/delay.h>
16#include <linux/io.h>
17#include <linux/slab.h>
18#include <linux/workqueue.h>
19#include <generated/utsrelease.h>
20
21#define DRIVERNAME "arm-charlcd"
22#define CHARLCD_TIMEOUT (msecs_to_jiffies(1000))
23
24/* Offsets to registers */
25#define CHAR_COM 0x00U
26#define CHAR_DAT 0x04U
27#define CHAR_RD 0x08U
28#define CHAR_RAW 0x0CU
29#define CHAR_MASK 0x10U
30#define CHAR_STAT 0x14U
31
32#define CHAR_RAW_CLEAR 0x00000000U
33#define CHAR_RAW_VALID 0x00000100U
34
35/* Hitachi HD44780 display commands */
36#define HD_CLEAR 0x01U
37#define HD_HOME 0x02U
38#define HD_ENTRYMODE 0x04U
39#define HD_ENTRYMODE_INCREMENT 0x02U
40#define HD_ENTRYMODE_SHIFT 0x01U
41#define HD_DISPCTRL 0x08U
42#define HD_DISPCTRL_ON 0x04U
43#define HD_DISPCTRL_CURSOR_ON 0x02U
44#define HD_DISPCTRL_CURSOR_BLINK 0x01U
45#define HD_CRSR_SHIFT 0x10U
46#define HD_CRSR_SHIFT_DISPLAY 0x08U
47#define HD_CRSR_SHIFT_DISPLAY_RIGHT 0x04U
48#define HD_FUNCSET 0x20U
49#define HD_FUNCSET_8BIT 0x10U
50#define HD_FUNCSET_2_LINES 0x08U
51#define HD_FUNCSET_FONT_5X10 0x04U
52#define HD_SET_CGRAM 0x40U
53#define HD_SET_DDRAM 0x80U
54#define HD_BUSY_FLAG 0x80U
55
56/**
57 * @dev: a pointer back to containing device
58 * @phybase: the offset to the controller in physical memory
59 * @physize: the size of the physical page
60 * @virtbase: the offset to the controller in virtual memory
61 * @irq: reserved interrupt number
62 * @complete: completion structure for the last LCD command
63 */
64struct charlcd {
65 struct device *dev;
66 u32 phybase;
67 u32 physize;
68 void __iomem *virtbase;
69 int irq;
70 struct completion complete;
71 struct delayed_work init_work;
72};
73
74static irqreturn_t charlcd_interrupt(int irq, void *data)
75{
76 struct charlcd *lcd = data;
77 u8 status;
78
79 status = readl(lcd->virtbase + CHAR_STAT) & 0x01;
80 /* Clear IRQ */
81 writel(CHAR_RAW_CLEAR, lcd->virtbase + CHAR_RAW);
82 if (status)
83 complete(&lcd->complete);
84 else
85 dev_info(lcd->dev, "Spurious IRQ (%02x)\n", status);
86 return IRQ_HANDLED;
87}
88
89
90static void charlcd_wait_complete_irq(struct charlcd *lcd)
91{
92 int ret;
93
94 ret = wait_for_completion_interruptible_timeout(&lcd->complete,
95 CHARLCD_TIMEOUT);
96 /* Disable IRQ after completion */
97 writel(0x00, lcd->virtbase + CHAR_MASK);
98
99 if (ret < 0) {
100 dev_err(lcd->dev,
101 "wait_for_completion_interruptible_timeout() "
102 "returned %d waiting for ready\n", ret);
103 return;
104 }
105
106 if (ret == 0) {
107 dev_err(lcd->dev, "charlcd controller timed out "
108 "waiting for ready\n");
109 return;
110 }
111}
112
113static u8 charlcd_4bit_read_char(struct charlcd *lcd)
114{
115 u8 data;
116 u32 val;
117 int i;
118
119 /* If we can, use an IRQ to wait for the data, else poll */
120 if (lcd->irq >= 0)
121 charlcd_wait_complete_irq(lcd);
122 else {
123 i = 0;
124 val = 0;
125 while (!(val & CHAR_RAW_VALID) && i < 10) {
126 udelay(100);
127 val = readl(lcd->virtbase + CHAR_RAW);
128 i++;
129 }
130
131 writel(CHAR_RAW_CLEAR, lcd->virtbase + CHAR_RAW);
132 }
133 msleep(1);
134
135 /* Read the 4 high bits of the data */
136 data = readl(lcd->virtbase + CHAR_RD) & 0xf0;
137
138 /*
139 * The second read for the low bits does not trigger an IRQ
140 * so in this case we have to poll for the 4 lower bits
141 */
142 i = 0;
143 val = 0;
144 while (!(val & CHAR_RAW_VALID) && i < 10) {
145 udelay(100);
146 val = readl(lcd->virtbase + CHAR_RAW);
147 i++;
148 }
149 writel(CHAR_RAW_CLEAR, lcd->virtbase + CHAR_RAW);
150 msleep(1);
151
152 /* Read the 4 low bits of the data */
153 data |= (readl(lcd->virtbase + CHAR_RD) >> 4) & 0x0f;
154
155 return data;
156}
157
158static bool charlcd_4bit_read_bf(struct charlcd *lcd)
159{
160 if (lcd->irq >= 0) {
161 /*
162 * If we'll use IRQs to wait for the busyflag, clear any
163 * pending flag and enable IRQ
164 */
165 writel(CHAR_RAW_CLEAR, lcd->virtbase + CHAR_RAW);
166 init_completion(&lcd->complete);
167 writel(0x01, lcd->virtbase + CHAR_MASK);
168 }
169 readl(lcd->virtbase + CHAR_COM);
170 return charlcd_4bit_read_char(lcd) & HD_BUSY_FLAG ? true : false;
171}
172
173static void charlcd_4bit_wait_busy(struct charlcd *lcd)
174{
175 int retries = 50;
176
177 udelay(100);
178 while (charlcd_4bit_read_bf(lcd) && retries)
179 retries--;
180 if (!retries)
181 dev_err(lcd->dev, "timeout waiting for busyflag\n");
182}
183
184static void charlcd_4bit_command(struct charlcd *lcd, u8 cmd)
185{
186 u32 cmdlo = (cmd << 4) & 0xf0;
187 u32 cmdhi = (cmd & 0xf0);
188
189 writel(cmdhi, lcd->virtbase + CHAR_COM);
190 udelay(10);
191 writel(cmdlo, lcd->virtbase + CHAR_COM);
192 charlcd_4bit_wait_busy(lcd);
193}
194
195static void charlcd_4bit_char(struct charlcd *lcd, u8 ch)
196{
197 u32 chlo = (ch << 4) & 0xf0;
198 u32 chhi = (ch & 0xf0);
199
200 writel(chhi, lcd->virtbase + CHAR_DAT);
201 udelay(10);
202 writel(chlo, lcd->virtbase + CHAR_DAT);
203 charlcd_4bit_wait_busy(lcd);
204}
205
206static void charlcd_4bit_print(struct charlcd *lcd, int line, const char *str)
207{
208 u8 offset;
209 int i;
210
211 /*
212 * We support line 0, 1
213 * Line 1 runs from 0x00..0x27
214 * Line 2 runs from 0x28..0x4f
215 */
216 if (line == 0)
217 offset = 0;
218 else if (line == 1)
219 offset = 0x28;
220 else
221 return;
222
223 /* Set offset */
224 charlcd_4bit_command(lcd, HD_SET_DDRAM | offset);
225
226 /* Send string */
227 for (i = 0; i < strlen(str) && i < 0x28; i++)
228 charlcd_4bit_char(lcd, str[i]);
229}
230
231static void charlcd_4bit_init(struct charlcd *lcd)
232{
233 /* These commands cannot be checked with the busy flag */
234 writel(HD_FUNCSET | HD_FUNCSET_8BIT, lcd->virtbase + CHAR_COM);
235 msleep(5);
236 writel(HD_FUNCSET | HD_FUNCSET_8BIT, lcd->virtbase + CHAR_COM);
237 udelay(100);
238 writel(HD_FUNCSET | HD_FUNCSET_8BIT, lcd->virtbase + CHAR_COM);
239 udelay(100);
240 /* Go to 4bit mode */
241 writel(HD_FUNCSET, lcd->virtbase + CHAR_COM);
242 udelay(100);
243 /*
244 * 4bit mode, 2 lines, 5x8 font, after this the number of lines
245 * and the font cannot be changed until the next initialization sequence
246 */
247 charlcd_4bit_command(lcd, HD_FUNCSET | HD_FUNCSET_2_LINES);
248 charlcd_4bit_command(lcd, HD_DISPCTRL | HD_DISPCTRL_ON);
249 charlcd_4bit_command(lcd, HD_ENTRYMODE | HD_ENTRYMODE_INCREMENT);
250 charlcd_4bit_command(lcd, HD_CLEAR);
251 charlcd_4bit_command(lcd, HD_HOME);
252 /* Put something useful in the display */
253 charlcd_4bit_print(lcd, 0, "ARM Linux");
254 charlcd_4bit_print(lcd, 1, UTS_RELEASE);
255}
256
257static void charlcd_init_work(struct work_struct *work)
258{
259 struct charlcd *lcd =
260 container_of(work, struct charlcd, init_work.work);
261
262 charlcd_4bit_init(lcd);
263}
264
265static int __init charlcd_probe(struct platform_device *pdev)
266{
267 int ret;
268 struct charlcd *lcd;
269 struct resource *res;
270
271 lcd = kzalloc(sizeof(struct charlcd), GFP_KERNEL);
272 if (!lcd)
273 return -ENOMEM;
274
275 lcd->dev = &pdev->dev;
276
277 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
278 if (!res) {
279 ret = -ENOENT;
280 goto out_no_resource;
281 }
282 lcd->phybase = res->start;
283 lcd->physize = resource_size(res);
284
285 if (request_mem_region(lcd->phybase, lcd->physize,
286 DRIVERNAME) == NULL) {
287 ret = -EBUSY;
288 goto out_no_memregion;
289 }
290
291 lcd->virtbase = ioremap(lcd->phybase, lcd->physize);
292 if (!lcd->virtbase) {
293 ret = -ENOMEM;
294 goto out_no_remap;
295 }
296
297 lcd->irq = platform_get_irq(pdev, 0);
298 /* If no IRQ is supplied, we'll survive without it */
299 if (lcd->irq >= 0) {
300 if (request_irq(lcd->irq, charlcd_interrupt, IRQF_DISABLED,
301 DRIVERNAME, lcd)) {
302 ret = -EIO;
303 goto out_no_irq;
304 }
305 }
306
307 platform_set_drvdata(pdev, lcd);
308
309 /*
310 * Initialize the display in a delayed work, because
311 * it is VERY slow and would slow down the boot of the system.
312 */
313 INIT_DELAYED_WORK(&lcd->init_work, charlcd_init_work);
314 schedule_delayed_work(&lcd->init_work, 0);
315
Uwe Kleine-Königb5950762010-11-01 15:38:34 -0400316 dev_info(&pdev->dev, "initialized ARM character LCD at %08x\n",
Linus Walleijce896242010-07-17 12:33:48 +0100317 lcd->phybase);
318
319 return 0;
320
321out_no_irq:
322 iounmap(lcd->virtbase);
323out_no_remap:
324 platform_set_drvdata(pdev, NULL);
325out_no_memregion:
326 release_mem_region(lcd->phybase, SZ_4K);
327out_no_resource:
328 kfree(lcd);
329 return ret;
330}
331
332static int __exit charlcd_remove(struct platform_device *pdev)
333{
334 struct charlcd *lcd = platform_get_drvdata(pdev);
335
336 if (lcd) {
337 free_irq(lcd->irq, lcd);
338 iounmap(lcd->virtbase);
339 release_mem_region(lcd->phybase, lcd->physize);
340 platform_set_drvdata(pdev, NULL);
341 kfree(lcd);
342 }
343
344 return 0;
345}
346
347static int charlcd_suspend(struct device *dev)
348{
349 struct platform_device *pdev = to_platform_device(dev);
350 struct charlcd *lcd = platform_get_drvdata(pdev);
351
352 /* Power the display off */
353 charlcd_4bit_command(lcd, HD_DISPCTRL);
354 return 0;
355}
356
357static int charlcd_resume(struct device *dev)
358{
359 struct platform_device *pdev = to_platform_device(dev);
360 struct charlcd *lcd = platform_get_drvdata(pdev);
361
362 /* Turn the display back on */
363 charlcd_4bit_command(lcd, HD_DISPCTRL | HD_DISPCTRL_ON);
364 return 0;
365}
366
367static const struct dev_pm_ops charlcd_pm_ops = {
368 .suspend = charlcd_suspend,
369 .resume = charlcd_resume,
370};
371
372static struct platform_driver charlcd_driver = {
373 .driver = {
374 .name = DRIVERNAME,
375 .owner = THIS_MODULE,
376 .pm = &charlcd_pm_ops,
377 },
378 .remove = __exit_p(charlcd_remove),
379};
380
381static int __init charlcd_init(void)
382{
383 return platform_driver_probe(&charlcd_driver, charlcd_probe);
384}
385
386static void __exit charlcd_exit(void)
387{
388 platform_driver_unregister(&charlcd_driver);
389}
390
391module_init(charlcd_init);
392module_exit(charlcd_exit);
393
394MODULE_AUTHOR("Linus Walleij <triad@df.lth.se>");
395MODULE_DESCRIPTION("ARM Character LCD Driver");
396MODULE_LICENSE("GPL v2");