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