linux/drivers/leds/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>
  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
  36enum r_tpu_pin { R_TPU_PIN_UNUSED, R_TPU_PIN_GPIO, R_TPU_PIN_GPIO_FN };
  37enum r_tpu_timer { R_TPU_TIMER_UNUSED, R_TPU_TIMER_ON };
  38
  39struct 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
  52static 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
  66static 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
  78static 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
  92static 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
 111static 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
 175static 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
 190static 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
 218static 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
 234static 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
 242static 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
 310static 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
 325static 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
 333module_platform_driver(r_tpu_device_driver);
 334
 335MODULE_AUTHOR("Magnus Damm");
 336MODULE_DESCRIPTION("Renesas TPU LED Driver");
 337MODULE_LICENSE("GPL v2");
 338
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