drivers/pwm/pwm-imx.c

   1 /*
   2  * simple driver for PWM (Pulse Width Modulator) controller
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  *
   8  * Derived from pxa PWM driver by eric miao <eric.miao@marvell.com>
   9  */
  10
  11 #include <linux/module.h>
  12 #include <linux/kernel.h>
  13 #include <linux/platform_device.h>
  14 #include <linux/slab.h>
  15 #include <linux/err.h>
  16 #include <linux/clk.h>
  17 #include <linux/delay.h>
  18 #include <linux/io.h>
  19 #include <linux/pwm.h>
  20 #include <linux/of.h>
  21 #include <linux/of_device.h>
  22
  23 /* i.MX1 and i.MX21 share the same PWM function block: */
  24
  25 #define MX1_PWMC                        0x00   /* PWM Control Register */
  26 #define MX1_PWMS                        0x04   /* PWM Sample Register */
  27 #define MX1_PWMP                        0x08   /* PWM Period Register */
  28
  29 #define MX1_PWMC_EN                     (1 << 4)
  30
  31 /* i.MX27, i.MX31, i.MX35 share the same PWM function block: */
  32
  33 #define MX3_PWMCR                       0x00    /* PWM Control Register */
  34 #define MX3_PWMSR                       0x04    /* PWM Status Register */
  35 #define MX3_PWMSAR                      0x0C    /* PWM Sample Register */
  36 #define MX3_PWMPR                       0x10    /* PWM Period Register */
  37 #define MX3_PWMCR_PRESCALER(x)          ((((x) - 1) & 0xFFF) << 4)
  38 #define MX3_PWMCR_DOZEEN                (1 << 24)
  39 #define MX3_PWMCR_WAITEN                (1 << 23)
  40 #define MX3_PWMCR_DBGEN                 (1 << 22)
  41 #define MX3_PWMCR_CLKSRC_IPG_HIGH       (2 << 16)
  42 #define MX3_PWMCR_CLKSRC_IPG            (1 << 16)
  43 #define MX3_PWMCR_SWR                   (1 << 3)
  44 #define MX3_PWMCR_EN                    (1 << 0)
  45 #define MX3_PWMSR_FIFOAV_4WORDS         0x4
  46 #define MX3_PWMSR_FIFOAV_MASK           0x7
  47
  48 #define MX3_PWM_SWR_LOOP                5
  49
  50 struct imx_chip {
  51         struct clk      *clk_per;
  52         struct clk      *clk_ipg;
  53
  54         void __iomem    *mmio_base;
  55
  56         struct pwm_chip chip;
  57
  58         int (*config)(struct pwm_chip *chip,
  59                 struct pwm_device *pwm, int duty_ns, int period_ns);
  60         void (*set_enable)(struct pwm_chip *chip, bool enable);
  61 };
  62
  63 #define to_imx_chip(chip)       container_of(chip, struct imx_chip, chip)
  64
  65 static int imx_pwm_config_v1(struct pwm_chip *chip,
  66                 struct pwm_device *pwm, int duty_ns, int period_ns)
  67 {
  68         struct imx_chip *imx = to_imx_chip(chip);
  69
  70         /*
  71          * The PWM subsystem allows for exact frequencies. However,
  72          * I cannot connect a scope on my device to the PWM line and
  73          * thus cannot provide the program the PWM controller
  74          * exactly. Instead, I'm relying on the fact that the
  75          * Bootloader (u-boot or WinCE+haret) has programmed the PWM
  76          * function group already. So I'll just modify the PWM sample
  77          * register to follow the ratio of duty_ns vs. period_ns
  78          * accordingly.
  79          *
  80          * This is good enough for programming the brightness of
  81          * the LCD backlight.
  82          *
  83          * The real implementation would divide PERCLK[0] first by
  84          * both the prescaler (/1 .. /128) and then by CLKSEL
  85          * (/2 .. /16).
  86          */
  87         u32 max = readl(imx->mmio_base + MX1_PWMP);
  88         u32 p = max * duty_ns / period_ns;
  89         writel(max - p, imx->mmio_base + MX1_PWMS);
  90
  91         return 0;
  92 }
  93
  94 static void imx_pwm_set_enable_v1(struct pwm_chip *chip, bool enable)
  95 {
  96         struct imx_chip *imx = to_imx_chip(chip);
  97         u32 val;
  98
  99         val = readl(imx->mmio_base + MX1_PWMC);
 100
 101         if (enable)
 102                 val |= MX1_PWMC_EN;
 103         else
 104                 val &= ~MX1_PWMC_EN;
 105
 106         writel(val, imx->mmio_base + MX1_PWMC);
 107 }
 108
 109 static int imx_pwm_config_v2(struct pwm_chip *chip,
 110                 struct pwm_device *pwm, int duty_ns, int period_ns)
 111 {
 112         struct imx_chip *imx = to_imx_chip(chip);
 113         struct device *dev = chip->dev;
 114         unsigned long long c;
 115         unsigned long period_cycles, duty_cycles, prescale;
 116         unsigned int period_ms;
 117         bool enable = pwm_is_enabled(pwm);
 118         int wait_count = 0, fifoav;
 119         u32 cr, sr;
 120
 121         /*
 122          * i.MX PWMv2 has a 4-word sample FIFO.
 123          * In order to avoid FIFO overflow issue, we do software reset
 124          * to clear all sample FIFO if the controller is disabled or
 125          * wait for a full PWM cycle to get a relinquished FIFO slot
 126          * when the controller is enabled and the FIFO is fully loaded.
 127          */
 128         if (enable) {
 129                 sr = readl(imx->mmio_base + MX3_PWMSR);
 130                 fifoav = sr & MX3_PWMSR_FIFOAV_MASK;
 131                 if (fifoav == MX3_PWMSR_FIFOAV_4WORDS) {
 132                         period_ms = DIV_ROUND_UP(pwm_get_period(pwm),
 133                                                  NSEC_PER_MSEC);
 134                         msleep(period_ms);
 135
 136                         sr = readl(imx->mmio_base + MX3_PWMSR);
 137                         if (fifoav == (sr & MX3_PWMSR_FIFOAV_MASK))
 138                                 dev_warn(dev, "there is no free FIFO slot\n");
 139                 }
 140         } else {
 141                 writel(MX3_PWMCR_SWR, imx->mmio_base + MX3_PWMCR);
 142                 do {
 143                         usleep_range(200, 1000);
 144                         cr = readl(imx->mmio_base + MX3_PWMCR);
 145                 } while ((cr & MX3_PWMCR_SWR) &&
 146                          (wait_count++ < MX3_PWM_SWR_LOOP));
 147
 148                 if (cr & MX3_PWMCR_SWR)
 149                         dev_warn(dev, "software reset timeout\n");
 150         }
 151
 152         c = clk_get_rate(imx->clk_per);
 153         c = c * period_ns;
 154         do_div(c, 1000000000);
 155         period_cycles = c;
 156
 157         prescale = period_cycles / 0x10000 + 1;
 158
 159         period_cycles /= prescale;
 160         c = (unsigned long long)period_cycles * duty_ns;
 161         do_div(c, period_ns);
 162         duty_cycles = c;
 163
 164         /*
 165          * according to imx pwm RM, the real period value should be
 166          * PERIOD value in PWMPR plus 2.
 167          */
 168         if (period_cycles > 2)
 169                 period_cycles -= 2;
 170         else
 171                 period_cycles = 0;
 172
 173         writel(duty_cycles, imx->mmio_base + MX3_PWMSAR);
 174         writel(period_cycles, imx->mmio_base + MX3_PWMPR);
 175
 176         cr = MX3_PWMCR_PRESCALER(prescale) |
 177                 MX3_PWMCR_DOZEEN | MX3_PWMCR_WAITEN |
 178                 MX3_PWMCR_DBGEN | MX3_PWMCR_CLKSRC_IPG_HIGH;
 179
 180         if (enable)
 181                 cr |= MX3_PWMCR_EN;
 182
 183         writel(cr, imx->mmio_base + MX3_PWMCR);
 184
 185         return 0;
 186 }
 187
 188 static void imx_pwm_set_enable_v2(struct pwm_chip *chip, bool enable)
 189 {
 190         struct imx_chip *imx = to_imx_chip(chip);
 191         u32 val;
 192
 193         val = readl(imx->mmio_base + MX3_PWMCR);
 194
 195         if (enable)
 196                 val |= MX3_PWMCR_EN;
 197         else
 198                 val &= ~MX3_PWMCR_EN;
 199
 200         writel(val, imx->mmio_base + MX3_PWMCR);
 201 }
 202
 203 static int imx_pwm_config(struct pwm_chip *chip,
 204                 struct pwm_device *pwm, int duty_ns, int period_ns)
 205 {
 206         struct imx_chip *imx = to_imx_chip(chip);
 207         int ret;
 208
 209         ret = clk_prepare_enable(imx->clk_ipg);
 210         if (ret)
 211                 return ret;
 212
 213         ret = imx->config(chip, pwm, duty_ns, period_ns);
 214
 215         clk_disable_unprepare(imx->clk_ipg);
 216
 217         return ret;
 218 }
 219
 220 static int imx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 221 {
 222         struct imx_chip *imx = to_imx_chip(chip);
 223         int ret;
 224
 225         ret = clk_prepare_enable(imx->clk_per);
 226         if (ret)
 227                 return ret;
 228
 229         imx->set_enable(chip, true);
 230
 231         return 0;
 232 }
 233
 234 static void imx_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 235 {
 236         struct imx_chip *imx = to_imx_chip(chip);
 237
 238         imx->set_enable(chip, false);
 239
 240         clk_disable_unprepare(imx->clk_per);
 241 }
 242
 243 static struct pwm_ops imx_pwm_ops = {
 244         .enable = imx_pwm_enable,
 245         .disable = imx_pwm_disable,
 246         .config = imx_pwm_config,
 247         .owner = THIS_MODULE,
 248 };
 249
 250 struct imx_pwm_data {
 251         int (*config)(struct pwm_chip *chip,
 252                 struct pwm_device *pwm, int duty_ns, int period_ns);
 253         void (*set_enable)(struct pwm_chip *chip, bool enable);
 254 };
 255
 256 static struct imx_pwm_data imx_pwm_data_v1 = {
 257         .config = imx_pwm_config_v1,
 258         .set_enable = imx_pwm_set_enable_v1,
 259 };
 260
 261 static struct imx_pwm_data imx_pwm_data_v2 = {
 262         .config = imx_pwm_config_v2,
 263         .set_enable = imx_pwm_set_enable_v2,
 264 };
 265
 266 static const struct of_device_id imx_pwm_dt_ids[] = {
 267         { .compatible = "fsl,imx1-pwm", .data = &imx_pwm_data_v1, },
 268         { .compatible = "fsl,imx27-pwm", .data = &imx_pwm_data_v2, },
 269         { /* sentinel */ }
 270 };
 271 MODULE_DEVICE_TABLE(of, imx_pwm_dt_ids);
 272
 273 static int imx_pwm_probe(struct platform_device *pdev)
 274 {
 275         const struct of_device_id *of_id =
 276                         of_match_device(imx_pwm_dt_ids, &pdev->dev);
 277         const struct imx_pwm_data *data;
 278         struct imx_chip *imx;
 279         struct resource *r;
 280         int ret = 0;
 281
 282         if (!of_id)
 283                 return -ENODEV;
 284
 285         imx = devm_kzalloc(&pdev->dev, sizeof(*imx), GFP_KERNEL);
 286         if (imx == NULL)
 287                 return -ENOMEM;
 288
 289         imx->clk_per = devm_clk_get(&pdev->dev, "per");
 290         if (IS_ERR(imx->clk_per)) {
 291                 dev_err(&pdev->dev, "getting per clock failed with %ld\n",
 292                                 PTR_ERR(imx->clk_per));
 293                 return PTR_ERR(imx->clk_per);
 294         }
 295
 296         imx->clk_ipg = devm_clk_get(&pdev->dev, "ipg");
 297         if (IS_ERR(imx->clk_ipg)) {
 298                 dev_err(&pdev->dev, "getting ipg clock failed with %ld\n",
 299                                 PTR_ERR(imx->clk_ipg));
 300                 return PTR_ERR(imx->clk_ipg);
 301         }
 302
 303         imx->chip.ops = &imx_pwm_ops;
 304         imx->chip.dev = &pdev->dev;
 305         imx->chip.base = -1;
 306         imx->chip.npwm = 1;
 307         imx->chip.can_sleep = true;
 308
 309         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 310         imx->mmio_base = devm_ioremap_resource(&pdev->dev, r);
 311         if (IS_ERR(imx->mmio_base))
 312                 return PTR_ERR(imx->mmio_base);
 313
 314         data = of_id->data;
 315         imx->config = data->config;
 316         imx->set_enable = data->set_enable;
 317
 318         ret = pwmchip_add(&imx->chip);
 319         if (ret < 0)
 320                 return ret;
 321
 322         platform_set_drvdata(pdev, imx);
 323         return 0;
 324 }
 325
 326 static int imx_pwm_remove(struct platform_device *pdev)
 327 {
 328         struct imx_chip *imx;
 329
 330         imx = platform_get_drvdata(pdev);
 331         if (imx == NULL)
 332                 return -ENODEV;
 333
 334         return pwmchip_remove(&imx->chip);
 335 }
 336
 337 static struct platform_driver imx_pwm_driver = {
 338         .driver         = {
 339                 .name   = "imx-pwm",
 340                 .of_match_table = imx_pwm_dt_ids,
 341         },
 342         .probe          = imx_pwm_probe,
 343         .remove         = imx_pwm_remove,
 344 };
 345
 346 module_platform_driver(imx_pwm_driver);
 347
 348 MODULE_LICENSE("GPL v2");
 349 MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>");