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         int             enabled;
  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 (imx->enabled)
 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         imx->enabled = 1;
 190
 191         return 0;
 192 }
 193
 194 static void imx_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 195 {
 196         struct imx_chip *imx = to_imx_chip(chip);
 197
 198         imx->set_enable(chip, false);
 199
 200         clk_disable_unprepare(imx->clk_per);
 201         imx->enabled = 0;
 202 }
 203
 204 static struct pwm_ops imx_pwm_ops = {
 205         .enable = imx_pwm_enable,
 206         .disable = imx_pwm_disable,
 207         .config = imx_pwm_config,
 208         .owner = THIS_MODULE,
 209 };
 210
 211 struct imx_pwm_data {
 212         int (*config)(struct pwm_chip *chip,
 213                 struct pwm_device *pwm, int duty_ns, int period_ns);
 214         void (*set_enable)(struct pwm_chip *chip, bool enable);
 215 };
 216
 217 static struct imx_pwm_data imx_pwm_data_v1 = {
 218         .config = imx_pwm_config_v1,
 219         .set_enable = imx_pwm_set_enable_v1,
 220 };
 221
 222 static struct imx_pwm_data imx_pwm_data_v2 = {
 223         .config = imx_pwm_config_v2,
 224         .set_enable = imx_pwm_set_enable_v2,
 225 };
 226
 227 static const struct of_device_id imx_pwm_dt_ids[] = {
 228         { .compatible = "fsl,imx1-pwm", .data = &imx_pwm_data_v1, },
 229         { .compatible = "fsl,imx27-pwm", .data = &imx_pwm_data_v2, },
 230         { /* sentinel */ }
 231 };
 232 MODULE_DEVICE_TABLE(of, imx_pwm_dt_ids);
 233
 234 static int imx_pwm_probe(struct platform_device *pdev)
 235 {
 236         const struct of_device_id *of_id =
 237                         of_match_device(imx_pwm_dt_ids, &pdev->dev);
 238         const struct imx_pwm_data *data;
 239         struct imx_chip *imx;
 240         struct resource *r;
 241         int ret = 0;
 242
 243         if (!of_id)
 244                 return -ENODEV;
 245
 246         imx = devm_kzalloc(&pdev->dev, sizeof(*imx), GFP_KERNEL);
 247         if (imx == NULL) {
 248                 dev_err(&pdev->dev, "failed to allocate memory\n");
 249                 return -ENOMEM;
 250         }
 251
 252         imx->clk_per = devm_clk_get(&pdev->dev, "per");
 253         if (IS_ERR(imx->clk_per)) {
 254                 dev_err(&pdev->dev, "getting per clock failed with %ld\n",
 255                                 PTR_ERR(imx->clk_per));
 256                 return PTR_ERR(imx->clk_per);
 257         }
 258
 259         imx->clk_ipg = devm_clk_get(&pdev->dev, "ipg");
 260         if (IS_ERR(imx->clk_ipg)) {
 261                 dev_err(&pdev->dev, "getting ipg clock failed with %ld\n",
 262                                 PTR_ERR(imx->clk_ipg));
 263                 return PTR_ERR(imx->clk_ipg);
 264         }
 265
 266         imx->chip.ops = &imx_pwm_ops;
 267         imx->chip.dev = &pdev->dev;
 268         imx->chip.base = -1;
 269         imx->chip.npwm = 1;
 270
 271         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 272         if (r == NULL) {
 273                 dev_err(&pdev->dev, "no memory resource defined\n");
 274                 return -ENODEV;
 275         }
 276
 277         imx->mmio_base = devm_ioremap_resource(&pdev->dev, r);
 278         if (IS_ERR(imx->mmio_base))
 279                 return PTR_ERR(imx->mmio_base);
 280
 281         data = of_id->data;
 282         imx->config = data->config;
 283         imx->set_enable = data->set_enable;
 284
 285         ret = pwmchip_add(&imx->chip);
 286         if (ret < 0)
 287                 return ret;
 288
 289         platform_set_drvdata(pdev, imx);
 290         return 0;
 291 }
 292
 293 static int imx_pwm_remove(struct platform_device *pdev)
 294 {
 295         struct imx_chip *imx;
 296
 297         imx = platform_get_drvdata(pdev);
 298         if (imx == NULL)
 299                 return -ENODEV;
 300
 301         return pwmchip_remove(&imx->chip);
 302 }
 303
 304 static struct platform_driver imx_pwm_driver = {
 305         .driver         = {
 306                 .name   = "imx-pwm",
 307                 .of_match_table = of_match_ptr(imx_pwm_dt_ids),
 308         },
 309         .probe          = imx_pwm_probe,
 310         .remove         = imx_pwm_remove,
 311 };
 312
 313 module_platform_driver(imx_pwm_driver);
 314
 315 MODULE_LICENSE("GPL v2");
 316 MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>");