linux/drivers/pwm/pwm-mxs.c
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   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
  39struct mxs_pwm_chip {
  40        struct pwm_chip chip;
  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
  47static 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
  98static 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
 112static 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
 121static 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
 128static 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        struct resource *res;
 133        struct pinctrl *pinctrl;
 134        int ret;
 135
 136        mxs = devm_kzalloc(&pdev->dev, sizeof(*mxs), GFP_KERNEL);
 137        if (!mxs)
 138                return -ENOMEM;
 139
 140        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 141        mxs->base = devm_ioremap_resource(&pdev->dev, res);
 142        if (IS_ERR(mxs->base))
 143                return PTR_ERR(mxs->base);
 144
 145        pinctrl = devm_pinctrl_get_select_default(&pdev->dev);
 146        if (IS_ERR(pinctrl))
 147                return PTR_ERR(pinctrl);
 148
 149        mxs->clk = devm_clk_get(&pdev->dev, NULL);
 150        if (IS_ERR(mxs->clk))
 151                return PTR_ERR(mxs->clk);
 152
 153        mxs->chip.dev = &pdev->dev;
 154        mxs->chip.ops = &mxs_pwm_ops;
 155        mxs->chip.base = -1;
 156        ret = of_property_read_u32(np, "fsl,pwm-number", &mxs->chip.npwm);
 157        if (ret < 0) {
 158                dev_err(&pdev->dev, "failed to get pwm number: %d\n", ret);
 159                return ret;
 160        }
 161
 162        ret = pwmchip_add(&mxs->chip);
 163        if (ret < 0) {
 164                dev_err(&pdev->dev, "failed to add pwm chip %d\n", ret);
 165                return ret;
 166        }
 167
 168        platform_set_drvdata(pdev, mxs);
 169
 170        stmp_reset_block(mxs->base);
 171
 172        return 0;
 173}
 174
 175static 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
 182static const struct of_device_id mxs_pwm_dt_ids[] = {
 183        { .compatible = "fsl,imx23-pwm", },
 184        { /* sentinel */ }
 185};
 186MODULE_DEVICE_TABLE(of, mxs_pwm_dt_ids);
 187
 188static struct platform_driver mxs_pwm_driver = {
 189        .driver = {
 190                .name = "mxs-pwm",
 191                .of_match_table = of_match_ptr(mxs_pwm_dt_ids),
 192        },
 193        .probe = mxs_pwm_probe,
 194        .remove = mxs_pwm_remove,
 195};
 196module_platform_driver(mxs_pwm_driver);
 197
 198MODULE_ALIAS("platform:mxs-pwm");
 199MODULE_AUTHOR("Shawn Guo <shawn.guo@linaro.org>");
 200MODULE_DESCRIPTION("Freescale MXS PWM Driver");
 201MODULE_LICENSE("GPL v2");
 202
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