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/io.h>
  18 #include <linux/pwm.h>
  19 #include <linux/of_device.h>
  20
  21 /* i.MX1 and i.MX21 share the same PWM function block: */
  22
  23 #define MX1_PWMC    0x00   /* PWM Control Register */
  24 #define MX1_PWMS    0x04   /* PWM Sample Register */
  25 #define MX1_PWMP    0x08   /* PWM Period Register */
  26
  27 #define MX1_PWMC_EN             (1 << 4)
  28
  29 /* i.MX27, i.MX31, i.MX35 share the same PWM function block: */
  30
  31 #define MX3_PWMCR                 0x00    /* PWM Control Register */
  32 #define MX3_PWMSAR                0x0C    /* PWM Sample Register */
  33 #define MX3_PWMPR                 0x10    /* PWM Period Register */
  34 #define MX3_PWMCR_PRESCALER(x)    (((x - 1) & 0xFFF) << 4)
  35 #define MX3_PWMCR_DOZEEN                (1 << 24)
  36 #define MX3_PWMCR_WAITEN                (1 << 23)
  37 #define MX3_PWMCR_DBGEN                 (1 << 22)
  38 #define MX3_PWMCR_CLKSRC_IPG_HIGH (2 << 16)
  39 #define MX3_PWMCR_CLKSRC_IPG      (1 << 16)
  40 #define MX3_PWMCR_EN              (1 << 0)
  41
  42 struct imx_chip {
  43         struct clk      *clk_per;
  44         struct clk      *clk_ipg;
  45
  46         void __iomem    *mmio_base;
  47
  48         struct pwm_chip chip;
  49
  50         int (*config)(struct pwm_chip *chip,
  51                 struct pwm_device *pwm, int duty_ns, int period_ns);
  52         void (*set_enable)(struct pwm_chip *chip, bool enable);
  53 };
  54
  55 #define to_imx_chip(chip)       container_of(chip, struct imx_chip, chip)
  56
  57 static int imx_pwm_config_v1(struct pwm_chip *chip,
  58                 struct pwm_device *pwm, int duty_ns, int period_ns)
  59 {
  60         struct imx_chip *imx = to_imx_chip(chip);
  61
  62         /*
  63          * The PWM subsystem allows for exact frequencies. However,
  64          * I cannot connect a scope on my device to the PWM line and
  65          * thus cannot provide the program the PWM controller
  66          * exactly. Instead, I'm relying on the fact that the
  67          * Bootloader (u-boot or WinCE+haret) has programmed the PWM
  68          * function group already. So I'll just modify the PWM sample
  69          * register to follow the ratio of duty_ns vs. period_ns
  70          * accordingly.
  71          *
  72          * This is good enough for programming the brightness of
  73          * the LCD backlight.
  74          *
  75          * The real implementation would divide PERCLK[0] first by
  76          * both the prescaler (/1 .. /128) and then by CLKSEL
  77          * (/2 .. /16).
  78          */
  79         u32 max = readl(imx->mmio_base + MX1_PWMP);
  80         u32 p = max * duty_ns / period_ns;
  81         writel(max - p, imx->mmio_base + MX1_PWMS);
  82
  83         return 0;
  84 }
  85
  86 static void imx_pwm_set_enable_v1(struct pwm_chip *chip, bool enable)
  87 {
  88         struct imx_chip *imx = to_imx_chip(chip);
  89         u32 val;
  90
  91         val = readl(imx->mmio_base + MX1_PWMC);
  92
  93         if (enable)
  94                 val |= MX1_PWMC_EN;
  95         else
  96                 val &= ~MX1_PWMC_EN;
  97
  98         writel(val, imx->mmio_base + MX1_PWMC);
  99 }
 100
 101 static int imx_pwm_config_v2(struct pwm_chip *chip,
 102                 struct pwm_device *pwm, int duty_ns, int period_ns)
 103 {
 104         struct imx_chip *imx = to_imx_chip(chip);
 105         unsigned long long c;
 106         unsigned long period_cycles, duty_cycles, prescale;
 107         u32 cr;
 108
 109         c = clk_get_rate(imx->clk_per);
 110         c = c * period_ns;
 111         do_div(c, 1000000000);
 112         period_cycles = c;
 113
 114         prescale = period_cycles / 0x10000 + 1;
 115
 116         period_cycles /= prescale;
 117         c = (unsigned long long)period_cycles * duty_ns;
 118         do_div(c, period_ns);
 119         duty_cycles = c;
 120
 121         /*
 122          * according to imx pwm RM, the real period value should be
 123          * PERIOD value in PWMPR plus 2.
 124          */
 125         if (period_cycles > 2)
 126                 period_cycles -= 2;
 127         else
 128                 period_cycles = 0;
 129
 130         writel(duty_cycles, imx->mmio_base + MX3_PWMSAR);
 131         writel(period_cycles, imx->mmio_base + MX3_PWMPR);
 132
 133         cr = MX3_PWMCR_PRESCALER(prescale) |
 134                 MX3_PWMCR_DOZEEN | MX3_PWMCR_WAITEN |
 135                 MX3_PWMCR_DBGEN | MX3_PWMCR_CLKSRC_IPG_HIGH;
 136
 137         if (test_bit(PWMF_ENABLED, &pwm->flags))
 138                 cr |= MX3_PWMCR_EN;
 139
 140         writel(cr, imx->mmio_base + MX3_PWMCR);
 141
 142         return 0;
 143 }
 144
 145 static void imx_pwm_set_enable_v2(struct pwm_chip *chip, bool enable)
 146 {
 147         struct imx_chip *imx = to_imx_chip(chip);
 148         u32 val;
 149
 150         val = readl(imx->mmio_base + MX3_PWMCR);
 151
 152         if (enable)
 153                 val |= MX3_PWMCR_EN;
 154         else
 155                 val &= ~MX3_PWMCR_EN;
 156
 157         writel(val, imx->mmio_base + MX3_PWMCR);
 158 }
 159
 160 static int imx_pwm_config(struct pwm_chip *chip,
 161                 struct pwm_device *pwm, int duty_ns, int period_ns)
 162 {
 163         struct imx_chip *imx = to_imx_chip(chip);
 164         int ret;
 165
 166         ret = clk_prepare_enable(imx->clk_ipg);
 167         if (ret)
 168                 return ret;
 169
 170         ret = imx->config(chip, pwm, duty_ns, period_ns);
 171
 172         clk_disable_unprepare(imx->clk_ipg);
 173
 174         return ret;
 175 }
 176
 177 static int imx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 178 {
 179         struct imx_chip *imx = to_imx_chip(chip);
 180         int ret;
 181
 182         ret = clk_prepare_enable(imx->clk_per);
 183         if (ret)
 184                 return ret;
 185
 186         imx->set_enable(chip, true);
 187
 188         return 0;
 189 }
 190
 191 static void imx_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 192 {
 193         struct imx_chip *imx = to_imx_chip(chip);
 194
 195         imx->set_enable(chip, false);
 196
 197         clk_disable_unprepare(imx->clk_per);
 198 }
 199
 200 static struct pwm_ops imx_pwm_ops = {
 201         .enable = imx_pwm_enable,
 202         .disable = imx_pwm_disable,
 203         .config = imx_pwm_config,
 204         .owner = THIS_MODULE,
 205 };
 206
 207 struct imx_pwm_data {
 208         int (*config)(struct pwm_chip *chip,
 209                 struct pwm_device *pwm, int duty_ns, int period_ns);
 210         void (*set_enable)(struct pwm_chip *chip, bool enable);
 211 };
 212
 213 static struct imx_pwm_data imx_pwm_data_v1 = {
 214         .config = imx_pwm_config_v1,
 215         .set_enable = imx_pwm_set_enable_v1,
 216 };
 217
 218 static struct imx_pwm_data imx_pwm_data_v2 = {
 219         .config = imx_pwm_config_v2,
 220         .set_enable = imx_pwm_set_enable_v2,
 221 };
 222
 223 static const struct of_device_id imx_pwm_dt_ids[] = {
 224         { .compatible = "fsl,imx1-pwm", .data = &imx_pwm_data_v1, },
 225         { .compatible = "fsl,imx27-pwm", .data = &imx_pwm_data_v2, },
 226         { /* sentinel */ }
 227 };
 228 MODULE_DEVICE_TABLE(of, imx_pwm_dt_ids);
 229
 230 static int imx_pwm_probe(struct platform_device *pdev)
 231 {
 232         const struct of_device_id *of_id =
 233                         of_match_device(imx_pwm_dt_ids, &pdev->dev);
 234         const struct imx_pwm_data *data;
 235         struct imx_chip *imx;
 236         struct resource *r;
 237         int ret = 0;
 238
 239         if (!of_id)
 240                 return -ENODEV;
 241
 242         imx = devm_kzalloc(&pdev->dev, sizeof(*imx), GFP_KERNEL);
 243         if (imx == NULL) {
 244                 dev_err(&pdev->dev, "failed to allocate memory\n");
 245                 return -ENOMEM;
 246         }
 247
 248         imx->clk_per = devm_clk_get(&pdev->dev, "per");
 249         if (IS_ERR(imx->clk_per)) {
 250                 dev_err(&pdev->dev, "getting per clock failed with %ld\n",
 251                                 PTR_ERR(imx->clk_per));
 252                 return PTR_ERR(imx->clk_per);
 253         }
 254
 255         imx->clk_ipg = devm_clk_get(&pdev->dev, "ipg");
 256         if (IS_ERR(imx->clk_ipg)) {
 257                 dev_err(&pdev->dev, "getting ipg clock failed with %ld\n",
 258                                 PTR_ERR(imx->clk_ipg));
 259                 return PTR_ERR(imx->clk_ipg);
 260         }
 261
 262         imx->chip.ops = &imx_pwm_ops;
 263         imx->chip.dev = &pdev->dev;
 264         imx->chip.base = -1;
 265         imx->chip.npwm = 1;
 266
 267         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 268         imx->mmio_base = devm_ioremap_resource(&pdev->dev, r);
 269         if (IS_ERR(imx->mmio_base))
 270                 return PTR_ERR(imx->mmio_base);
 271
 272         data = of_id->data;
 273         imx->config = data->config;
 274         imx->set_enable = data->set_enable;
 275
 276         ret = pwmchip_add(&imx->chip);
 277         if (ret < 0)
 278                 return ret;
 279
 280         platform_set_drvdata(pdev, imx);
 281         return 0;
 282 }
 283
 284 static int imx_pwm_remove(struct platform_device *pdev)
 285 {
 286         struct imx_chip *imx;
 287
 288         imx = platform_get_drvdata(pdev);
 289         if (imx == NULL)
 290                 return -ENODEV;
 291
 292         return pwmchip_remove(&imx->chip);
 293 }
 294
 295 static struct platform_driver imx_pwm_driver = {
 296         .driver         = {
 297                 .name   = "imx-pwm",
 298                 .of_match_table = of_match_ptr(imx_pwm_dt_ids),
 299         },
 300         .probe          = imx_pwm_probe,
 301         .remove         = imx_pwm_remove,
 302 };
 303
 304 module_platform_driver(imx_pwm_driver);
 305
 306 MODULE_LICENSE("GPL v2");
 307 MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>");