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