1 /*
2 * LED control using Renesas TPU
3 *
4 * Copyright (C) 2011 Magnus Damm
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18 */
19
20 #include <linux/module.h>
21 #include <linux/init.h>
22 #include <linux/platform_device.h>
23 #include <linux/spinlock.h>
24 #include <linux/printk.h>
25 #include <linux/ioport.h>
26 #include <linux/io.h>
27 #include <linux/clk.h>
28 #include <linux/leds.h>
29 #include <linux/platform_data/leds-renesas-tpu.h>
30 #include <linux/gpio.h>
31 #include <linux/err.h>
32 #include <linux/slab.h>
33 #include <linux/pm_runtime.h>
34 #include <linux/workqueue.h>
35
36 enum r_tpu_pin { R_TPU_PIN_UNUSED, R_TPU_PIN_GPIO, R_TPU_PIN_GPIO_FN };
37 enum r_tpu_timer { R_TPU_TIMER_UNUSED, R_TPU_TIMER_ON };
38
39 struct r_tpu_priv {
40 struct led_classdev ldev;
41 void __iomem *mapbase;
42 struct clk *clk;
43 struct platform_device *pdev;
44 enum r_tpu_pin pin_state;
45 enum r_tpu_timer timer_state;
46 unsigned long min_rate;
47 unsigned int refresh_rate;
48 struct work_struct work;
49 enum led_brightness new_brightness;
50 };
51
52 static DEFINE_SPINLOCK(r_tpu_lock);
53
54 #define TSTR -1 /* Timer start register (shared register) */
55 #define TCR 0 /* Timer control register (+0x00) */
56 #define TMDR 1 /* Timer mode register (+0x04) */
57 #define TIOR 2 /* Timer I/O control register (+0x08) */
58 #define TIER 3 /* Timer interrupt enable register (+0x0c) */
59 #define TSR 4 /* Timer status register (+0x10) */
60 #define TCNT 5 /* Timer counter (+0x14) */
61 #define TGRA 6 /* Timer general register A (+0x18) */
62 #define TGRB 7 /* Timer general register B (+0x1c) */
63 #define TGRC 8 /* Timer general register C (+0x20) */
64 #define TGRD 9 /* Timer general register D (+0x24) */
65
r_tpu_read(struct r_tpu_priv * p,int reg_nr)66 static inline unsigned short r_tpu_read(struct r_tpu_priv *p, int reg_nr)
67 {
68 struct led_renesas_tpu_config *cfg = p->pdev->dev.platform_data;
69 void __iomem *base = p->mapbase;
70 unsigned long offs = reg_nr << 2;
71
72 if (reg_nr == TSTR)
73 return ioread16(base - cfg->channel_offset);
74
75 return ioread16(base + offs);
76 }
77
r_tpu_write(struct r_tpu_priv * p,int reg_nr,unsigned short value)78 static inline void r_tpu_write(struct r_tpu_priv *p, int reg_nr,
79 unsigned short value)
80 {
81 struct led_renesas_tpu_config *cfg = p->pdev->dev.platform_data;
82 void __iomem *base = p->mapbase;
83 unsigned long offs = reg_nr << 2;
84
85 if (reg_nr == TSTR) {
86 iowrite16(value, base - cfg->channel_offset);
87 return;
88 }
89
90 iowrite16(value, base + offs);
91 }
92
r_tpu_start_stop_ch(struct r_tpu_priv * p,int start)93 static void r_tpu_start_stop_ch(struct r_tpu_priv *p, int start)
94 {
95 struct led_renesas_tpu_config *cfg = p->pdev->dev.platform_data;
96 unsigned long flags, value;
97
98 /* start stop register shared by multiple timer channels */
99 spin_lock_irqsave(&r_tpu_lock, flags);
100 value = r_tpu_read(p, TSTR);
101
102 if (start)
103 value |= 1 << cfg->timer_bit;
104 else
105 value &= ~(1 << cfg->timer_bit);
106
107 r_tpu_write(p, TSTR, value);
108 spin_unlock_irqrestore(&r_tpu_lock, flags);
109 }
110
r_tpu_enable(struct r_tpu_priv * p,enum led_brightness brightness)111 static int r_tpu_enable(struct r_tpu_priv *p, enum led_brightness brightness)
112 {
113 struct led_renesas_tpu_config *cfg = p->pdev->dev.platform_data;
114 int prescaler[] = { 1, 4, 16, 64 };
115 int k, ret;
116 unsigned long rate, tmp;
117
118 if (p->timer_state == R_TPU_TIMER_ON)
119 return 0;
120
121 /* wake up device and enable clock */
122 pm_runtime_get_sync(&p->pdev->dev);
123 ret = clk_enable(p->clk);
124 if (ret) {
125 dev_err(&p->pdev->dev, "cannot enable clock\n");
126 return ret;
127 }
128
129 /* make sure channel is disabled */
130 r_tpu_start_stop_ch(p, 0);
131
132 /* get clock rate after enabling it */
133 rate = clk_get_rate(p->clk);
134
135 /* pick the lowest acceptable rate */
136 for (k = 0; k < ARRAY_SIZE(prescaler); k++)
137 if ((rate / prescaler[k]) < p->min_rate)
138 break;
139
140 if (!k) {
141 dev_err(&p->pdev->dev, "clock rate mismatch\n");
142 goto err0;
143 }
144 dev_dbg(&p->pdev->dev, "rate = %lu, prescaler %u\n",
145 rate, prescaler[k - 1]);
146
147 /* clear TCNT on TGRB match, count on rising edge, set prescaler */
148 r_tpu_write(p, TCR, 0x0040 | (k - 1));
149
150 /* output 0 until TGRA, output 1 until TGRB */
151 r_tpu_write(p, TIOR, 0x0002);
152
153 rate /= prescaler[k - 1] * p->refresh_rate;
154 r_tpu_write(p, TGRB, rate);
155 dev_dbg(&p->pdev->dev, "TRGB = 0x%04lx\n", rate);
156
157 tmp = (cfg->max_brightness - brightness) * rate;
158 r_tpu_write(p, TGRA, tmp / cfg->max_brightness);
159 dev_dbg(&p->pdev->dev, "TRGA = 0x%04lx\n", tmp / cfg->max_brightness);
160
161 /* PWM mode */
162 r_tpu_write(p, TMDR, 0x0002);
163
164 /* enable channel */
165 r_tpu_start_stop_ch(p, 1);
166
167 p->timer_state = R_TPU_TIMER_ON;
168 return 0;
169 err0:
170 clk_disable(p->clk);
171 pm_runtime_put_sync(&p->pdev->dev);
172 return -ENOTSUPP;
173 }
174
r_tpu_disable(struct r_tpu_priv * p)175 static void r_tpu_disable(struct r_tpu_priv *p)
176 {
177 if (p->timer_state == R_TPU_TIMER_UNUSED)
178 return;
179
180 /* disable channel */
181 r_tpu_start_stop_ch(p, 0);
182
183 /* stop clock and mark device as idle */
184 clk_disable(p->clk);
185 pm_runtime_put_sync(&p->pdev->dev);
186
187 p->timer_state = R_TPU_TIMER_UNUSED;
188 }
189
r_tpu_set_pin(struct r_tpu_priv * p,enum r_tpu_pin new_state,enum led_brightness brightness)190 static void r_tpu_set_pin(struct r_tpu_priv *p, enum r_tpu_pin new_state,
191 enum led_brightness brightness)
192 {
193 struct led_renesas_tpu_config *cfg = p->pdev->dev.platform_data;
194
195 if (p->pin_state == new_state) {
196 if (p->pin_state == R_TPU_PIN_GPIO)
197 gpio_set_value(cfg->pin_gpio, brightness);
198 return;
199 }
200
201 if (p->pin_state == R_TPU_PIN_GPIO)
202 gpio_free(cfg->pin_gpio);
203
204 if (p->pin_state == R_TPU_PIN_GPIO_FN)
205 gpio_free(cfg->pin_gpio_fn);
206
207 if (new_state == R_TPU_PIN_GPIO) {
208 gpio_request(cfg->pin_gpio, cfg->name);
209 gpio_direction_output(cfg->pin_gpio, !!brightness);
210 }
211 if (new_state == R_TPU_PIN_GPIO_FN)
212 gpio_request(cfg->pin_gpio_fn, cfg->name);
213
214 p->pin_state = new_state;
215 }
216
r_tpu_work(struct work_struct * work)217 static void r_tpu_work(struct work_struct *work)
218 {
219 struct r_tpu_priv *p = container_of(work, struct r_tpu_priv, work);
220 enum led_brightness brightness = p->new_brightness;
221
222 r_tpu_disable(p);
223
224 /* off and maximum are handled as GPIO pins, in between PWM */
225 if ((brightness == 0) || (brightness == p->ldev.max_brightness))
226 r_tpu_set_pin(p, R_TPU_PIN_GPIO, brightness);
227 else {
228 r_tpu_set_pin(p, R_TPU_PIN_GPIO_FN, 0);
229 r_tpu_enable(p, brightness);
230 }
231 }
232
r_tpu_set_brightness(struct led_classdev * ldev,enum led_brightness brightness)233 static void r_tpu_set_brightness(struct led_classdev *ldev,
234 enum led_brightness brightness)
235 {
236 struct r_tpu_priv *p = container_of(ldev, struct r_tpu_priv, ldev);
237 p->new_brightness = brightness;
238 schedule_work(&p->work);
239 }
240
r_tpu_probe(struct platform_device * pdev)241 static int __devinit r_tpu_probe(struct platform_device *pdev)
242 {
243 struct led_renesas_tpu_config *cfg = pdev->dev.platform_data;
244 struct r_tpu_priv *p;
245 struct resource *res;
246 int ret = -ENXIO;
247
248 if (!cfg) {
249 dev_err(&pdev->dev, "missing platform data\n");
250 goto err0;
251 }
252
253 p = kzalloc(sizeof(*p), GFP_KERNEL);
254 if (p == NULL) {
255 dev_err(&pdev->dev, "failed to allocate driver data\n");
256 ret = -ENOMEM;
257 goto err0;
258 }
259
260 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
261 if (!res) {
262 dev_err(&pdev->dev, "failed to get I/O memory\n");
263 goto err1;
264 }
265
266 /* map memory, let mapbase point to our channel */
267 p->mapbase = ioremap_nocache(res->start, resource_size(res));
268 if (p->mapbase == NULL) {
269 dev_err(&pdev->dev, "failed to remap I/O memory\n");
270 goto err1;
271 }
272
273 /* get hold of clock */
274 p->clk = clk_get(&pdev->dev, NULL);
275 if (IS_ERR(p->clk)) {
276 dev_err(&pdev->dev, "cannot get clock\n");
277 ret = PTR_ERR(p->clk);
278 goto err2;
279 }
280
281 p->pdev = pdev;
282 p->pin_state = R_TPU_PIN_UNUSED;
283 p->timer_state = R_TPU_TIMER_UNUSED;
284 p->refresh_rate = cfg->refresh_rate ? cfg->refresh_rate : 100;
285 r_tpu_set_pin(p, R_TPU_PIN_GPIO, LED_OFF);
286 platform_set_drvdata(pdev, p);
287
288 INIT_WORK(&p->work, r_tpu_work);
289
290 p->ldev.name = cfg->name;
291 p->ldev.brightness = LED_OFF;
292 p->ldev.max_brightness = cfg->max_brightness;
293 p->ldev.brightness_set = r_tpu_set_brightness;
294 p->ldev.flags |= LED_CORE_SUSPENDRESUME;
295 ret = led_classdev_register(&pdev->dev, &p->ldev);
296 if (ret < 0)
297 goto err3;
298
299 /* max_brightness may be updated by the LED core code */
300 p->min_rate = p->ldev.max_brightness * p->refresh_rate;
301
302 pm_runtime_enable(&pdev->dev);
303 return 0;
304
305 err3:
306 r_tpu_set_pin(p, R_TPU_PIN_UNUSED, LED_OFF);
307 clk_put(p->clk);
308 err2:
309 iounmap(p->mapbase);
310 err1:
311 kfree(p);
312 err0:
313 return ret;
314 }
315
r_tpu_remove(struct platform_device * pdev)316 static int __devexit r_tpu_remove(struct platform_device *pdev)
317 {
318 struct r_tpu_priv *p = platform_get_drvdata(pdev);
319
320 r_tpu_set_brightness(&p->ldev, LED_OFF);
321 led_classdev_unregister(&p->ldev);
322 cancel_work_sync(&p->work);
323 r_tpu_disable(p);
324 r_tpu_set_pin(p, R_TPU_PIN_UNUSED, LED_OFF);
325
326 pm_runtime_disable(&pdev->dev);
327 clk_put(p->clk);
328
329 iounmap(p->mapbase);
330 kfree(p);
331 return 0;
332 }
333
334 static struct platform_driver r_tpu_device_driver = {
335 .probe = r_tpu_probe,
336 .remove = __devexit_p(r_tpu_remove),
337 .driver = {
338 .name = "leds-renesas-tpu",
339 }
340 };
341
342 module_platform_driver(r_tpu_device_driver);
343
344 MODULE_AUTHOR("Magnus Damm");
345 MODULE_DESCRIPTION("Renesas TPU LED Driver");
346 MODULE_LICENSE("GPL v2");
347