drivers/pwm/pwm-mxs.c

   1 /*
   2  * Copyright 2012 Freescale Semiconductor, Inc.
   3  *
   4  * The code contained herein is licensed under the GNU General Public
   5  * License. You may obtain a copy of the GNU General Public License
   6  * Version 2 or later at the following locations:
   7  *
   8  * http://www.opensource.org/licenses/gpl-license.html
   9  * http://www.gnu.org/copyleft/gpl.html
  10  */
  11
  12 #include <linux/clk.h>
  13 #include <linux/err.h>
  14 #include <linux/io.h>
  15 #include <linux/kernel.h>
  16 #include <linux/module.h>
  17 #include <linux/of.h>
  18 #include <linux/of_address.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/pwm.h>
  21 #include <linux/slab.h>
  22 #include <linux/stmp_device.h>
  23
  24 #define SET     0x4
  25 #define CLR     0x8
  26 #define TOG     0xc
  27
  28 #define PWM_CTRL                0x0
  29 #define PWM_ACTIVE0             0x10
  30 #define PWM_PERIOD0             0x20
  31 #define  PERIOD_PERIOD(p)       ((p) & 0xffff)
  32 #define  PERIOD_PERIOD_MAX      0x10000
  33 #define  PERIOD_ACTIVE_HIGH     (3 << 16)
  34 #define  PERIOD_INACTIVE_LOW    (2 << 18)
  35 #define  PERIOD_CDIV(div)       (((div) & 0x7) << 20)
  36 #define  PERIOD_CDIV_MAX        8
  37
  38 struct mxs_pwm_chip {
  39         struct pwm_chip chip;
  40         struct clk *clk;
  41         void __iomem *base;
  42 };
  43
  44 #define to_mxs_pwm_chip(_chip) container_of(_chip, struct mxs_pwm_chip, chip)
  45
  46 static int mxs_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
  47                           int duty_ns, int period_ns)
  48 {
  49         struct mxs_pwm_chip *mxs = to_mxs_pwm_chip(chip);
  50         int ret, div = 0;
  51         unsigned int period_cycles, duty_cycles;
  52         unsigned long rate;
  53         unsigned long long c;
  54
  55         rate = clk_get_rate(mxs->clk);
  56         while (1) {
  57                 c = rate / (1 << div);
  58                 c = c * period_ns;
  59                 do_div(c, 1000000000);
  60                 if (c < PERIOD_PERIOD_MAX)
  61                         break;
  62                 div++;
  63                 if (div > PERIOD_CDIV_MAX)
  64                         return -EINVAL;
  65         }
  66
  67         period_cycles = c;
  68         c *= duty_ns;
  69         do_div(c, period_ns);
  70         duty_cycles = c;
  71
  72         /*
  73          * If the PWM channel is disabled, make sure to turn on the clock
  74          * before writing the register. Otherwise, keep it enabled.
  75          */
  76         if (!test_bit(PWMF_ENABLED, &pwm->flags)) {
  77                 ret = clk_prepare_enable(mxs->clk);
  78                 if (ret)
  79                         return ret;
  80         }
  81
  82         writel(duty_cycles << 16,
  83                         mxs->base + PWM_ACTIVE0 + pwm->hwpwm * 0x20);
  84         writel(PERIOD_PERIOD(period_cycles) | PERIOD_ACTIVE_HIGH |
  85                PERIOD_INACTIVE_LOW | PERIOD_CDIV(div),
  86                         mxs->base + PWM_PERIOD0 + pwm->hwpwm * 0x20);
  87
  88         /*
  89          * If the PWM is not enabled, turn the clock off again to save power.
  90          */
  91         if (!test_bit(PWMF_ENABLED, &pwm->flags))
  92                 clk_disable_unprepare(mxs->clk);
  93
  94         return 0;
  95 }
  96
  97 static int mxs_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
  98 {
  99         struct mxs_pwm_chip *mxs = to_mxs_pwm_chip(chip);
 100         int ret;
 101
 102         ret = clk_prepare_enable(mxs->clk);
 103         if (ret)
 104                 return ret;
 105
 106         writel(1 << pwm->hwpwm, mxs->base + PWM_CTRL + SET);
 107
 108         return 0;
 109 }
 110
 111 static void mxs_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 112 {
 113         struct mxs_pwm_chip *mxs = to_mxs_pwm_chip(chip);
 114
 115         writel(1 << pwm->hwpwm, mxs->base + PWM_CTRL + CLR);
 116
 117         clk_disable_unprepare(mxs->clk);
 118 }
 119
 120 static const struct pwm_ops mxs_pwm_ops = {
 121         .config = mxs_pwm_config,
 122         .enable = mxs_pwm_enable,
 123         .disable = mxs_pwm_disable,
 124         .owner = THIS_MODULE,
 125 };
 126
 127 static int mxs_pwm_probe(struct platform_device *pdev)
 128 {
 129         struct device_node *np = pdev->dev.of_node;
 130         struct mxs_pwm_chip *mxs;
 131         struct resource *res;
 132         int ret;
 133
 134         mxs = devm_kzalloc(&pdev->dev, sizeof(*mxs), GFP_KERNEL);
 135         if (!mxs)
 136                 return -ENOMEM;
 137
 138         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 139         mxs->base = devm_ioremap_resource(&pdev->dev, res);
 140         if (IS_ERR(mxs->base))
 141                 return PTR_ERR(mxs->base);
 142
 143         mxs->clk = devm_clk_get(&pdev->dev, NULL);
 144         if (IS_ERR(mxs->clk))
 145                 return PTR_ERR(mxs->clk);
 146
 147         mxs->chip.dev = &pdev->dev;
 148         mxs->chip.ops = &mxs_pwm_ops;
 149         mxs->chip.base = -1;
 150         ret = of_property_read_u32(np, "fsl,pwm-number", &mxs->chip.npwm);
 151         if (ret < 0) {
 152                 dev_err(&pdev->dev, "failed to get pwm number: %d\n", ret);
 153                 return ret;
 154         }
 155
 156         ret = pwmchip_add(&mxs->chip);
 157         if (ret < 0) {
 158                 dev_err(&pdev->dev, "failed to add pwm chip %d\n", ret);
 159                 return ret;
 160         }
 161
 162         platform_set_drvdata(pdev, mxs);
 163
 164         ret = stmp_reset_block(mxs->base);
 165         if (ret)
 166                 goto pwm_remove;
 167
 168         return 0;
 169
 170 pwm_remove:
 171         pwmchip_remove(&mxs->chip);
 172         return ret;
 173 }
 174
 175 static int mxs_pwm_remove(struct platform_device *pdev)
 176 {
 177         struct mxs_pwm_chip *mxs = platform_get_drvdata(pdev);
 178
 179         return pwmchip_remove(&mxs->chip);
 180 }
 181
 182 static const struct of_device_id mxs_pwm_dt_ids[] = {
 183         { .compatible = "fsl,imx23-pwm", },
 184         { /* sentinel */ }
 185 };
 186 MODULE_DEVICE_TABLE(of, mxs_pwm_dt_ids);
 187
 188 static struct platform_driver mxs_pwm_driver = {
 189         .driver = {
 190                 .name = "mxs-pwm",
 191                 .owner = THIS_MODULE,
 192                 .of_match_table = mxs_pwm_dt_ids,
 193         },
 194         .probe = mxs_pwm_probe,
 195         .remove = mxs_pwm_remove,
 196 };
 197 module_platform_driver(mxs_pwm_driver);
 198
 199 MODULE_ALIAS("platform:mxs-pwm");
 200 MODULE_AUTHOR("Shawn Guo <shawn.guo@linaro.org>");
 201 MODULE_DESCRIPTION("Freescale MXS PWM Driver");
 202 MODULE_LICENSE("GPL v2");