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leds-renesas-tpu.c
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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>
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 
38 
39 struct r_tpu_priv {
42  struct clk *clk;
46  unsigned long min_rate;
47  unsigned int refresh_rate;
48  struct work_struct work;
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 
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 
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 
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 
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 
168  return 0;
169  err0:
170  clk_disable(p->clk);
171  pm_runtime_put_sync(&p->pdev->dev);
172  return -ENOTSUPP;
173 }
174 
175 static void r_tpu_disable(struct r_tpu_priv *p)
176 {
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 
188 }
189 
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 
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 
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);
238  schedule_work(&p->work);
239 }
240 
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;
247 
248  if (!cfg) {
249  dev_err(&pdev->dev, "missing platform data\n");
250  return -ENODEV;
251  }
252 
253  p = devm_kzalloc(&pdev->dev, sizeof(*p), GFP_KERNEL);
254  if (p == NULL) {
255  dev_err(&pdev->dev, "failed to allocate driver data\n");
256  return -ENOMEM;
257  }
258 
259  res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
260  if (!res) {
261  dev_err(&pdev->dev, "failed to get I/O memory\n");
262  return -ENXIO;
263  }
264 
265  /* map memory, let mapbase point to our channel */
266  p->mapbase = ioremap_nocache(res->start, resource_size(res));
267  if (p->mapbase == NULL) {
268  dev_err(&pdev->dev, "failed to remap I/O memory\n");
269  return -ENXIO;
270  }
271 
272  /* get hold of clock */
273  p->clk = clk_get(&pdev->dev, NULL);
274  if (IS_ERR(p->clk)) {
275  dev_err(&pdev->dev, "cannot get clock\n");
276  ret = PTR_ERR(p->clk);
277  goto err0;
278  }
279 
280  p->pdev = pdev;
283  p->refresh_rate = cfg->refresh_rate ? cfg->refresh_rate : 100;
284  r_tpu_set_pin(p, R_TPU_PIN_GPIO, LED_OFF);
285  platform_set_drvdata(pdev, p);
286 
287  INIT_WORK(&p->work, r_tpu_work);
288 
289  p->ldev.name = cfg->name;
290  p->ldev.brightness = LED_OFF;
291  p->ldev.max_brightness = cfg->max_brightness;
292  p->ldev.brightness_set = r_tpu_set_brightness;
293  p->ldev.flags |= LED_CORE_SUSPENDRESUME;
294  ret = led_classdev_register(&pdev->dev, &p->ldev);
295  if (ret < 0)
296  goto err1;
297 
298  /* max_brightness may be updated by the LED core code */
299  p->min_rate = p->ldev.max_brightness * p->refresh_rate;
300 
301  pm_runtime_enable(&pdev->dev);
302  return 0;
303 
304  err1:
305  r_tpu_set_pin(p, R_TPU_PIN_UNUSED, LED_OFF);
306  clk_put(p->clk);
307  err0:
308  iounmap(p->mapbase);
309  return ret;
310 }
311 
312 static int __devexit r_tpu_remove(struct platform_device *pdev)
313 {
314  struct r_tpu_priv *p = platform_get_drvdata(pdev);
315 
316  r_tpu_set_brightness(&p->ldev, LED_OFF);
318  cancel_work_sync(&p->work);
319  r_tpu_disable(p);
320  r_tpu_set_pin(p, R_TPU_PIN_UNUSED, LED_OFF);
321 
322  pm_runtime_disable(&pdev->dev);
323  clk_put(p->clk);
324 
325  iounmap(p->mapbase);
326  return 0;
327 }
328 
329 static struct platform_driver r_tpu_device_driver = {
330  .probe = r_tpu_probe,
331  .remove = __devexit_p(r_tpu_remove),
332  .driver = {
333  .name = "leds-renesas-tpu",
334  }
335 };
336 
337 module_platform_driver(r_tpu_device_driver);
338 
339 MODULE_AUTHOR("Magnus Damm");
340 MODULE_DESCRIPTION("Renesas TPU LED Driver");
341 MODULE_LICENSE("GPL v2");