drivers/pwm/pwm-berlin.c

   1 /*
   2  * Marvell Berlin PWM driver
   3  *
   4  * Copyright (C) 2015 Marvell Technology Group Ltd.
   5  *
   6  * Author: Antoine Tenart <antoine.tenart@free-electrons.com>
   7  *
   8  * This file is licensed under the terms of the GNU General Public
   9  * License version 2. This program is licensed "as is" without any
  10  * warranty of any kind, whether express or implied.
  11  */
  12
  13 #include <linux/clk.h>
  14 #include <linux/io.h>
  15 #include <linux/kernel.h>
  16 #include <linux/module.h>
  17 #include <linux/platform_device.h>
  18 #include <linux/pwm.h>
  19
  20 #define BERLIN_PWM_EN                   0x0
  21 #define  BERLIN_PWM_ENABLE              BIT(0)
  22 #define BERLIN_PWM_CONTROL              0x4
  23 #define  BERLIN_PWM_PRESCALE_MASK       0x7
  24 #define  BERLIN_PWM_PRESCALE_MAX        4096
  25 #define  BERLIN_PWM_INVERT_POLARITY     BIT(3)
  26 #define BERLIN_PWM_DUTY                 0x8
  27 #define BERLIN_PWM_TCNT                 0xc
  28 #define  BERLIN_PWM_MAX_TCNT            65535
  29
  30 struct berlin_pwm_chip {
  31         struct pwm_chip chip;
  32         struct clk *clk;
  33         void __iomem *base;
  34 };
  35
  36 static inline struct berlin_pwm_chip *to_berlin_pwm_chip(struct pwm_chip *chip)
  37 {
  38         return container_of(chip, struct berlin_pwm_chip, chip);
  39 }
  40
  41 static const u32 prescaler_table[] = {
  42         1, 4, 8, 16, 64, 256, 1024, 4096
  43 };
  44
  45 static inline u32 berlin_pwm_readl(struct berlin_pwm_chip *chip,
  46                                    unsigned int channel, unsigned long offset)
  47 {
  48         return readl_relaxed(chip->base + channel * 0x10 + offset);
  49 }
  50
  51 static inline void berlin_pwm_writel(struct berlin_pwm_chip *chip,
  52                                      unsigned int channel, u32 value,
  53                                      unsigned long offset)
  54 {
  55         writel_relaxed(value, chip->base + channel * 0x10 + offset);
  56 }
  57
  58 static int berlin_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm_dev,
  59                              int duty_ns, int period_ns)
  60 {
  61         struct berlin_pwm_chip *pwm = to_berlin_pwm_chip(chip);
  62         unsigned int prescale;
  63         u32 value, duty, period;
  64         u64 cycles, tmp;
  65
  66         cycles = clk_get_rate(pwm->clk);
  67         cycles *= period_ns;
  68         do_div(cycles, NSEC_PER_SEC);
  69
  70         for (prescale = 0; prescale < ARRAY_SIZE(prescaler_table); prescale++) {
  71                 tmp = cycles;
  72                 do_div(tmp, prescaler_table[prescale]);
  73
  74                 if (tmp <= BERLIN_PWM_MAX_TCNT)
  75                         break;
  76         }
  77
  78         if (tmp > BERLIN_PWM_MAX_TCNT)
  79                 return -ERANGE;
  80
  81         period = tmp;
  82         cycles = tmp * duty_ns;
  83         do_div(cycles, period_ns);
  84         duty = cycles;
  85
  86         value = berlin_pwm_readl(pwm, pwm_dev->hwpwm, BERLIN_PWM_CONTROL);
  87         value &= ~BERLIN_PWM_PRESCALE_MASK;
  88         value |= prescale;
  89         berlin_pwm_writel(pwm, pwm_dev->hwpwm, value, BERLIN_PWM_CONTROL);
  90
  91         berlin_pwm_writel(pwm, pwm_dev->hwpwm, duty, BERLIN_PWM_DUTY);
  92         berlin_pwm_writel(pwm, pwm_dev->hwpwm, period, BERLIN_PWM_TCNT);
  93
  94         return 0;
  95 }
  96
  97 static int berlin_pwm_set_polarity(struct pwm_chip *chip,
  98                                    struct pwm_device *pwm_dev,
  99                                    enum pwm_polarity polarity)
 100 {
 101         struct berlin_pwm_chip *pwm = to_berlin_pwm_chip(chip);
 102         u32 value;
 103
 104         value = berlin_pwm_readl(pwm, pwm_dev->hwpwm, BERLIN_PWM_CONTROL);
 105
 106         if (polarity == PWM_POLARITY_NORMAL)
 107                 value &= ~BERLIN_PWM_INVERT_POLARITY;
 108         else
 109                 value |= BERLIN_PWM_INVERT_POLARITY;
 110
 111         berlin_pwm_writel(pwm, pwm_dev->hwpwm, value, BERLIN_PWM_CONTROL);
 112
 113         return 0;
 114 }
 115
 116 static int berlin_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm_dev)
 117 {
 118         struct berlin_pwm_chip *pwm = to_berlin_pwm_chip(chip);
 119         u32 value;
 120
 121         value = berlin_pwm_readl(pwm, pwm_dev->hwpwm, BERLIN_PWM_EN);
 122         value |= BERLIN_PWM_ENABLE;
 123         berlin_pwm_writel(pwm, pwm_dev->hwpwm, value, BERLIN_PWM_EN);
 124
 125         return 0;
 126 }
 127
 128 static void berlin_pwm_disable(struct pwm_chip *chip,
 129                                struct pwm_device *pwm_dev)
 130 {
 131         struct berlin_pwm_chip *pwm = to_berlin_pwm_chip(chip);
 132         u32 value;
 133
 134         value = berlin_pwm_readl(pwm, pwm_dev->hwpwm, BERLIN_PWM_EN);
 135         value &= ~BERLIN_PWM_ENABLE;
 136         berlin_pwm_writel(pwm, pwm_dev->hwpwm, value, BERLIN_PWM_EN);
 137 }
 138
 139 static const struct pwm_ops berlin_pwm_ops = {
 140         .config = berlin_pwm_config,
 141         .set_polarity = berlin_pwm_set_polarity,
 142         .enable = berlin_pwm_enable,
 143         .disable = berlin_pwm_disable,
 144         .owner = THIS_MODULE,
 145 };
 146
 147 static const struct of_device_id berlin_pwm_match[] = {
 148         { .compatible = "marvell,berlin-pwm" },
 149         { },
 150 };
 151 MODULE_DEVICE_TABLE(of, berlin_pwm_match);
 152
 153 static int berlin_pwm_probe(struct platform_device *pdev)
 154 {
 155         struct berlin_pwm_chip *pwm;
 156         struct resource *res;
 157         int ret;
 158
 159         pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
 160         if (!pwm)
 161                 return -ENOMEM;
 162
 163         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 164         pwm->base = devm_ioremap_resource(&pdev->dev, res);
 165         if (IS_ERR(pwm->base))
 166                 return PTR_ERR(pwm->base);
 167
 168         pwm->clk = devm_clk_get(&pdev->dev, NULL);
 169         if (IS_ERR(pwm->clk))
 170                 return PTR_ERR(pwm->clk);
 171
 172         ret = clk_prepare_enable(pwm->clk);
 173         if (ret)
 174                 return ret;
 175
 176         pwm->chip.dev = &pdev->dev;
 177         pwm->chip.ops = &berlin_pwm_ops;
 178         pwm->chip.base = -1;
 179         pwm->chip.npwm = 4;
 180         pwm->chip.can_sleep = true;
 181         pwm->chip.of_xlate = of_pwm_xlate_with_flags;
 182         pwm->chip.of_pwm_n_cells = 3;
 183
 184         ret = pwmchip_add(&pwm->chip);
 185         if (ret < 0) {
 186                 dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret);
 187                 clk_disable_unprepare(pwm->clk);
 188                 return ret;
 189         }
 190
 191         platform_set_drvdata(pdev, pwm);
 192
 193         return 0;
 194 }
 195
 196 static int berlin_pwm_remove(struct platform_device *pdev)
 197 {
 198         struct berlin_pwm_chip *pwm = platform_get_drvdata(pdev);
 199         int ret;
 200
 201         ret = pwmchip_remove(&pwm->chip);
 202         clk_disable_unprepare(pwm->clk);
 203
 204         return ret;
 205 }
 206
 207 static struct platform_driver berlin_pwm_driver = {
 208         .probe = berlin_pwm_probe,
 209         .remove = berlin_pwm_remove,
 210         .driver = {
 211                 .name = "berlin-pwm",
 212                 .of_match_table = berlin_pwm_match,
 213         },
 214 };
 215 module_platform_driver(berlin_pwm_driver);
 216
 217 MODULE_AUTHOR("Antoine Tenart <antoine.tenart@free-electrons.com>");
 218 MODULE_DESCRIPTION("Marvell Berlin PWM driver");
 219 MODULE_LICENSE("GPL v2");