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 static const unsigned int cdiv[PERIOD_CDIV_MAX] = {
  39         1, 2, 4, 8, 16, 64, 256, 1024
  40 };
  41
  42 struct mxs_pwm_chip {
  43         struct pwm_chip chip;
  44         struct clk *clk;
  45         void __iomem *base;
  46 };
  47
  48 #define to_mxs_pwm_chip(_chip) container_of(_chip, struct mxs_pwm_chip, chip)
  49
  50 static int mxs_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
  51                           int duty_ns, int period_ns)
  52 {
  53         struct mxs_pwm_chip *mxs = to_mxs_pwm_chip(chip);
  54         int ret, div = 0;
  55         unsigned int period_cycles, duty_cycles;
  56         unsigned long rate;
  57         unsigned long long c;
  58
  59         rate = clk_get_rate(mxs->clk);
  60         while (1) {
  61                 c = rate / cdiv[div];
  62                 c = c * period_ns;
  63                 do_div(c, 1000000000);
  64                 if (c < PERIOD_PERIOD_MAX)
  65                         break;
  66                 div++;
  67                 if (div >= PERIOD_CDIV_MAX)
  68                         return -EINVAL;
  69         }
  70
  71         period_cycles = c;
  72         c *= duty_ns;
  73         do_div(c, period_ns);
  74         duty_cycles = c;
  75
  76         /*
  77          * If the PWM channel is disabled, make sure to turn on the clock
  78          * before writing the register. Otherwise, keep it enabled.
  79          */
  80         if (!pwm_is_enabled(pwm)) {
  81                 ret = clk_prepare_enable(mxs->clk);
  82                 if (ret)
  83                         return ret;
  84         }
  85
  86         writel(duty_cycles << 16,
  87                         mxs->base + PWM_ACTIVE0 + pwm->hwpwm * 0x20);
  88         writel(PERIOD_PERIOD(period_cycles) | PERIOD_ACTIVE_HIGH |
  89                PERIOD_INACTIVE_LOW | PERIOD_CDIV(div),
  90                         mxs->base + PWM_PERIOD0 + pwm->hwpwm * 0x20);
  91
  92         /*
  93          * If the PWM is not enabled, turn the clock off again to save power.
  94          */
  95         if (!pwm_is_enabled(pwm))
  96                 clk_disable_unprepare(mxs->clk);
  97
  98         return 0;
  99 }
 100
 101 static int mxs_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 102 {
 103         struct mxs_pwm_chip *mxs = to_mxs_pwm_chip(chip);
 104         int ret;
 105
 106         ret = clk_prepare_enable(mxs->clk);
 107         if (ret)
 108                 return ret;
 109
 110         writel(1 << pwm->hwpwm, mxs->base + PWM_CTRL + SET);
 111
 112         return 0;
 113 }
 114
 115 static void mxs_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 116 {
 117         struct mxs_pwm_chip *mxs = to_mxs_pwm_chip(chip);
 118
 119         writel(1 << pwm->hwpwm, mxs->base + PWM_CTRL + CLR);
 120
 121         clk_disable_unprepare(mxs->clk);
 122 }
 123
 124 static const struct pwm_ops mxs_pwm_ops = {
 125         .config = mxs_pwm_config,
 126         .enable = mxs_pwm_enable,
 127         .disable = mxs_pwm_disable,
 128         .owner = THIS_MODULE,
 129 };
 130
 131 static int mxs_pwm_probe(struct platform_device *pdev)
 132 {
 133         struct device_node *np = pdev->dev.of_node;
 134         struct mxs_pwm_chip *mxs;
 135         struct resource *res;
 136         int ret;
 137
 138         mxs = devm_kzalloc(&pdev->dev, sizeof(*mxs), GFP_KERNEL);
 139         if (!mxs)
 140                 return -ENOMEM;
 141
 142         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 143         mxs->base = devm_ioremap_resource(&pdev->dev, res);
 144         if (IS_ERR(mxs->base))
 145                 return PTR_ERR(mxs->base);
 146
 147         mxs->clk = devm_clk_get(&pdev->dev, NULL);
 148         if (IS_ERR(mxs->clk))
 149                 return PTR_ERR(mxs->clk);
 150
 151         mxs->chip.dev = &pdev->dev;
 152         mxs->chip.ops = &mxs_pwm_ops;
 153         mxs->chip.base = -1;
 154         mxs->chip.can_sleep = true;
 155         ret = of_property_read_u32(np, "fsl,pwm-number", &mxs->chip.npwm);
 156         if (ret < 0) {
 157                 dev_err(&pdev->dev, "failed to get pwm number: %d\n", ret);
 158                 return ret;
 159         }
 160
 161         ret = pwmchip_add(&mxs->chip);
 162         if (ret < 0) {
 163                 dev_err(&pdev->dev, "failed to add pwm chip %d\n", ret);
 164                 return ret;
 165         }
 166
 167         platform_set_drvdata(pdev, mxs);
 168
 169         ret = stmp_reset_block(mxs->base);
 170         if (ret)
 171                 goto pwm_remove;
 172
 173         return 0;
 174
 175 pwm_remove:
 176         pwmchip_remove(&mxs->chip);
 177         return ret;
 178 }
 179
 180 static int mxs_pwm_remove(struct platform_device *pdev)
 181 {
 182         struct mxs_pwm_chip *mxs = platform_get_drvdata(pdev);
 183
 184         return pwmchip_remove(&mxs->chip);
 185 }
 186
 187 static const struct of_device_id mxs_pwm_dt_ids[] = {
 188         { .compatible = "fsl,imx23-pwm", },
 189         { /* sentinel */ }
 190 };
 191 MODULE_DEVICE_TABLE(of, mxs_pwm_dt_ids);
 192
 193 static struct platform_driver mxs_pwm_driver = {
 194         .driver = {
 195                 .name = "mxs-pwm",
 196                 .of_match_table = mxs_pwm_dt_ids,
 197         },
 198         .probe = mxs_pwm_probe,
 199         .remove = mxs_pwm_remove,
 200 };
 201 module_platform_driver(mxs_pwm_driver);
 202
 203 MODULE_ALIAS("platform:mxs-pwm");
 204 MODULE_AUTHOR("Shawn Guo <shawn.guo@linaro.org>");
 205 MODULE_DESCRIPTION("Freescale MXS PWM Driver");
 206 MODULE_LICENSE("GPL v2");