drivers/pwm/pwm-bcm2835.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright 2014 Bart Tanghe <bart.tanghe@thomasmore.be>
   4  */
   5
   6 #include <linux/clk.h>
   7 #include <linux/err.h>
   8 #include <linux/io.h>
   9 #include <linux/module.h>
  10 #include <linux/of.h>
  11 #include <linux/platform_device.h>
  12 #include <linux/pwm.h>
  13
  14 #define PWM_CONTROL             0x000
  15 #define PWM_CONTROL_SHIFT(x)    ((x) * 8)
  16 #define PWM_CONTROL_MASK        0xff
  17 #define PWM_MODE                0x80            /* set timer in PWM mode */
  18 #define PWM_ENABLE              (1 << 0)
  19 #define PWM_POLARITY            (1 << 4)
  20
  21 #define PERIOD(x)               (((x) * 0x10) + 0x10)
  22 #define DUTY(x)                 (((x) * 0x10) + 0x14)
  23
  24 #define MIN_PERIOD              108             /* 9.2 MHz max. PWM clock */
  25
  26 struct bcm2835_pwm {
  27         struct pwm_chip chip;
  28         struct device *dev;
  29         void __iomem *base;
  30         struct clk *clk;
  31 };
  32
  33 static inline struct bcm2835_pwm *to_bcm2835_pwm(struct pwm_chip *chip)
  34 {
  35         return container_of(chip, struct bcm2835_pwm, chip);
  36 }
  37
  38 static int bcm2835_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
  39 {
  40         struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
  41         u32 value;
  42
  43         value = readl(pc->base + PWM_CONTROL);
  44         value &= ~(PWM_CONTROL_MASK << PWM_CONTROL_SHIFT(pwm->hwpwm));
  45         value |= (PWM_MODE << PWM_CONTROL_SHIFT(pwm->hwpwm));
  46         writel(value, pc->base + PWM_CONTROL);
  47
  48         return 0;
  49 }
  50
  51 static void bcm2835_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
  52 {
  53         struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
  54         u32 value;
  55
  56         value = readl(pc->base + PWM_CONTROL);
  57         value &= ~(PWM_CONTROL_MASK << PWM_CONTROL_SHIFT(pwm->hwpwm));
  58         writel(value, pc->base + PWM_CONTROL);
  59 }
  60
  61 static int bcm2835_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
  62                               int duty_ns, int period_ns)
  63 {
  64         struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
  65         unsigned long rate = clk_get_rate(pc->clk);
  66         unsigned long scaler;
  67
  68         if (!rate) {
  69                 dev_err(pc->dev, "failed to get clock rate\n");
  70                 return -EINVAL;
  71         }
  72
  73         scaler = DIV_ROUND_CLOSEST(NSEC_PER_SEC, rate);
  74
  75         if (period_ns <= MIN_PERIOD) {
  76                 dev_err(pc->dev, "period %d not supported, minimum %d\n",
  77                         period_ns, MIN_PERIOD);
  78                 return -EINVAL;
  79         }
  80
  81         writel(DIV_ROUND_CLOSEST(duty_ns, scaler),
  82                pc->base + DUTY(pwm->hwpwm));
  83         writel(DIV_ROUND_CLOSEST(period_ns, scaler),
  84                pc->base + PERIOD(pwm->hwpwm));
  85
  86         return 0;
  87 }
  88
  89 static int bcm2835_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
  90 {
  91         struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
  92         u32 value;
  93
  94         value = readl(pc->base + PWM_CONTROL);
  95         value |= PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm);
  96         writel(value, pc->base + PWM_CONTROL);
  97
  98         return 0;
  99 }
 100
 101 static void bcm2835_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 102 {
 103         struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
 104         u32 value;
 105
 106         value = readl(pc->base + PWM_CONTROL);
 107         value &= ~(PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm));
 108         writel(value, pc->base + PWM_CONTROL);
 109 }
 110
 111 static int bcm2835_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
 112                                 enum pwm_polarity polarity)
 113 {
 114         struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
 115         u32 value;
 116
 117         value = readl(pc->base + PWM_CONTROL);
 118
 119         if (polarity == PWM_POLARITY_NORMAL)
 120                 value &= ~(PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm));
 121         else
 122                 value |= PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm);
 123
 124         writel(value, pc->base + PWM_CONTROL);
 125
 126         return 0;
 127 }
 128
 129 static const struct pwm_ops bcm2835_pwm_ops = {
 130         .request = bcm2835_pwm_request,
 131         .free = bcm2835_pwm_free,
 132         .config = bcm2835_pwm_config,
 133         .enable = bcm2835_pwm_enable,
 134         .disable = bcm2835_pwm_disable,
 135         .set_polarity = bcm2835_set_polarity,
 136         .owner = THIS_MODULE,
 137 };
 138
 139 static int bcm2835_pwm_probe(struct platform_device *pdev)
 140 {
 141         struct bcm2835_pwm *pc;
 142         struct resource *res;
 143         int ret;
 144
 145         pc = devm_kzalloc(&pdev->dev, sizeof(*pc), GFP_KERNEL);
 146         if (!pc)
 147                 return -ENOMEM;
 148
 149         pc->dev = &pdev->dev;
 150
 151         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 152         pc->base = devm_ioremap_resource(&pdev->dev, res);
 153         if (IS_ERR(pc->base))
 154                 return PTR_ERR(pc->base);
 155
 156         pc->clk = devm_clk_get(&pdev->dev, NULL);
 157         if (IS_ERR(pc->clk)) {
 158                 dev_err(&pdev->dev, "clock not found: %ld\n", PTR_ERR(pc->clk));
 159                 return PTR_ERR(pc->clk);
 160         }
 161
 162         ret = clk_prepare_enable(pc->clk);
 163         if (ret)
 164                 return ret;
 165
 166         pc->chip.dev = &pdev->dev;
 167         pc->chip.ops = &bcm2835_pwm_ops;
 168         pc->chip.npwm = 2;
 169         pc->chip.of_xlate = of_pwm_xlate_with_flags;
 170         pc->chip.of_pwm_n_cells = 3;
 171
 172         platform_set_drvdata(pdev, pc);
 173
 174         ret = pwmchip_add(&pc->chip);
 175         if (ret < 0)
 176                 goto add_fail;
 177
 178         return 0;
 179
 180 add_fail:
 181         clk_disable_unprepare(pc->clk);
 182         return ret;
 183 }
 184
 185 static int bcm2835_pwm_remove(struct platform_device *pdev)
 186 {
 187         struct bcm2835_pwm *pc = platform_get_drvdata(pdev);
 188
 189         clk_disable_unprepare(pc->clk);
 190
 191         return pwmchip_remove(&pc->chip);
 192 }
 193
 194 static const struct of_device_id bcm2835_pwm_of_match[] = {
 195         { .compatible = "brcm,bcm2835-pwm", },
 196         { /* sentinel */ }
 197 };
 198 MODULE_DEVICE_TABLE(of, bcm2835_pwm_of_match);
 199
 200 static struct platform_driver bcm2835_pwm_driver = {
 201         .driver = {
 202                 .name = "bcm2835-pwm",
 203                 .of_match_table = bcm2835_pwm_of_match,
 204         },
 205         .probe = bcm2835_pwm_probe,
 206         .remove = bcm2835_pwm_remove,
 207 };
 208 module_platform_driver(bcm2835_pwm_driver);
 209
 210 MODULE_AUTHOR("Bart Tanghe <bart.tanghe@thomasmore.be>");
 211 MODULE_DESCRIPTION("Broadcom BCM2835 PWM driver");
 212 MODULE_LICENSE("GPL v2");