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