drivers/leds/leds-renesas-tpu.c

   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
  66 static inline u16 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, u16 value)
  79 {
  80         struct led_renesas_tpu_config *cfg = p->pdev->dev.platform_data;
  81         void __iomem *base = p->mapbase;
  82         unsigned long offs = reg_nr << 2;
  83
  84         if (reg_nr == TSTR) {
  85                 iowrite16(value, base - cfg->channel_offset);
  86                 return;
  87         }
  88
  89         iowrite16(value, base + offs);
  90 }
  91
  92 static void r_tpu_start_stop_ch(struct r_tpu_priv *p, int start)
  93 {
  94         struct led_renesas_tpu_config *cfg = p->pdev->dev.platform_data;
  95         unsigned long flags;
  96         u16 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 = ARRAY_SIZE(prescaler) - 1; k >= 0; k--)
 137                 if ((rate / prescaler[k]) >= p->min_rate)
 138                         break;
 139
 140         if (k < 0) {
 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]);
 146
 147         /* clear TCNT on TGRB match, count on rising edge, set prescaler */
 148         r_tpu_write(p, TCR, 0x0040 | k);
 149
 150         /* output 0 until TGRA, output 1 until TGRB */
 151         r_tpu_write(p, TIOR, 0x0002);
 152
 153         rate /= prescaler[k] * 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
 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
 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_one(cfg->pin_gpio, !!brightness ?
 209                                 GPIOF_OUT_INIT_HIGH : GPIOF_OUT_INIT_LOW,
 210                                 cfg->name);
 211
 212         if (new_state == R_TPU_PIN_GPIO_FN)
 213                 gpio_request(cfg->pin_gpio_fn, cfg->name);
 214
 215         p->pin_state = new_state;
 216 }
 217
 218 static void r_tpu_work(struct work_struct *work)
 219 {
 220         struct r_tpu_priv *p = container_of(work, struct r_tpu_priv, work);
 221         enum led_brightness brightness = p->new_brightness;
 222
 223         r_tpu_disable(p);
 224
 225         /* off and maximum are handled as GPIO pins, in between PWM */
 226         if ((brightness == 0) || (brightness == p->ldev.max_brightness))
 227                 r_tpu_set_pin(p, R_TPU_PIN_GPIO, brightness);
 228         else {
 229                 r_tpu_set_pin(p, R_TPU_PIN_GPIO_FN, 0);
 230                 r_tpu_enable(p, brightness);
 231         }
 232 }
 233
 234 static void r_tpu_set_brightness(struct led_classdev *ldev,
 235                                  enum led_brightness brightness)
 236 {
 237         struct r_tpu_priv *p = container_of(ldev, struct r_tpu_priv, ldev);
 238         p->new_brightness = brightness;
 239         schedule_work(&p->work);
 240 }
 241
 242 static int r_tpu_probe(struct platform_device *pdev)
 243 {
 244         struct led_renesas_tpu_config *cfg = pdev->dev.platform_data;
 245         struct r_tpu_priv *p;
 246         struct resource *res;
 247         int ret;
 248
 249         if (!cfg) {
 250                 dev_err(&pdev->dev, "missing platform data\n");
 251                 return -ENODEV;
 252         }
 253
 254         p = devm_kzalloc(&pdev->dev, sizeof(*p), GFP_KERNEL);
 255         if (p == NULL) {
 256                 dev_err(&pdev->dev, "failed to allocate driver data\n");
 257                 return -ENOMEM;
 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                 return -ENXIO;
 264         }
 265
 266         /* map memory, let mapbase point to our channel */
 267         p->mapbase = devm_ioremap_nocache(&pdev->dev, res->start,
 268                                         resource_size(res));
 269         if (p->mapbase == NULL) {
 270                 dev_err(&pdev->dev, "failed to remap I/O memory\n");
 271                 return -ENXIO;
 272         }
 273
 274         /* get hold of clock */
 275         p->clk = devm_clk_get(&pdev->dev, NULL);
 276         if (IS_ERR(p->clk)) {
 277                 dev_err(&pdev->dev, "cannot get clock\n");
 278                 return PTR_ERR(p->clk);
 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 err0;
 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  err0:
 306         r_tpu_set_pin(p, R_TPU_PIN_UNUSED, LED_OFF);
 307         return ret;
 308 }
 309
 310 static int r_tpu_remove(struct platform_device *pdev)
 311 {
 312         struct r_tpu_priv *p = platform_get_drvdata(pdev);
 313
 314         r_tpu_set_brightness(&p->ldev, LED_OFF);
 315         led_classdev_unregister(&p->ldev);
 316         cancel_work_sync(&p->work);
 317         r_tpu_disable(p);
 318         r_tpu_set_pin(p, R_TPU_PIN_UNUSED, LED_OFF);
 319
 320         pm_runtime_disable(&pdev->dev);
 321
 322         return 0;
 323 }
 324
 325 static struct platform_driver r_tpu_device_driver = {
 326         .probe          = r_tpu_probe,
 327         .remove         = r_tpu_remove,
 328         .driver         = {
 329                 .name   = "leds-renesas-tpu",
 330         }
 331 };
 332
 333 module_platform_driver(r_tpu_device_driver);
 334
 335 MODULE_AUTHOR("Magnus Damm");
 336 MODULE_DESCRIPTION("Renesas TPU LED Driver");
 337 MODULE_LICENSE("GPL v2");