drivers/pwm/pwm-bcm-iproc.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 // Copyright (C) 2016 Broadcom
   3
   4 #include <linux/clk.h>
   5 #include <linux/delay.h>
   6 #include <linux/err.h>
   7 #include <linux/io.h>
   8 #include <linux/math64.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 IPROC_PWM_CTRL_OFFSET                   0x00
  15 #define IPROC_PWM_CTRL_TYPE_SHIFT(ch)           (15 + (ch))
  16 #define IPROC_PWM_CTRL_POLARITY_SHIFT(ch)       (8 + (ch))
  17 #define IPROC_PWM_CTRL_EN_SHIFT(ch)             (ch)
  18
  19 #define IPROC_PWM_PERIOD_OFFSET(ch)             (0x04 + ((ch) << 3))
  20 #define IPROC_PWM_PERIOD_MIN                    0x02
  21 #define IPROC_PWM_PERIOD_MAX                    0xffff
  22
  23 #define IPROC_PWM_DUTY_CYCLE_OFFSET(ch)         (0x08 + ((ch) << 3))
  24 #define IPROC_PWM_DUTY_CYCLE_MIN                0x00
  25 #define IPROC_PWM_DUTY_CYCLE_MAX                0xffff
  26
  27 #define IPROC_PWM_PRESCALE_OFFSET               0x24
  28 #define IPROC_PWM_PRESCALE_BITS                 0x06
  29 #define IPROC_PWM_PRESCALE_SHIFT(ch)            ((3 - (ch)) * \
  30                                                  IPROC_PWM_PRESCALE_BITS)
  31 #define IPROC_PWM_PRESCALE_MASK(ch)             (IPROC_PWM_PRESCALE_MAX << \
  32                                                  IPROC_PWM_PRESCALE_SHIFT(ch))
  33 #define IPROC_PWM_PRESCALE_MIN                  0x00
  34 #define IPROC_PWM_PRESCALE_MAX                  0x3f
  35
  36 struct iproc_pwmc {
  37         struct pwm_chip chip;
  38         void __iomem *base;
  39         struct clk *clk;
  40 };
  41
  42 static inline struct iproc_pwmc *to_iproc_pwmc(struct pwm_chip *chip)
  43 {
  44         return container_of(chip, struct iproc_pwmc, chip);
  45 }
  46
  47 static void iproc_pwmc_enable(struct iproc_pwmc *ip, unsigned int channel)
  48 {
  49         u32 value;
  50
  51         value = readl(ip->base + IPROC_PWM_CTRL_OFFSET);
  52         value |= 1 << IPROC_PWM_CTRL_EN_SHIFT(channel);
  53         writel(value, ip->base + IPROC_PWM_CTRL_OFFSET);
  54
  55         /* must be a 400 ns delay between clearing and setting enable bit */
  56         ndelay(400);
  57 }
  58
  59 static void iproc_pwmc_disable(struct iproc_pwmc *ip, unsigned int channel)
  60 {
  61         u32 value;
  62
  63         value = readl(ip->base + IPROC_PWM_CTRL_OFFSET);
  64         value &= ~(1 << IPROC_PWM_CTRL_EN_SHIFT(channel));
  65         writel(value, ip->base + IPROC_PWM_CTRL_OFFSET);
  66
  67         /* must be a 400 ns delay between clearing and setting enable bit */
  68         ndelay(400);
  69 }
  70
  71 static int iproc_pwmc_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
  72                                 struct pwm_state *state)
  73 {
  74         struct iproc_pwmc *ip = to_iproc_pwmc(chip);
  75         u64 tmp, multi, rate;
  76         u32 value, prescale;
  77
  78         value = readl(ip->base + IPROC_PWM_CTRL_OFFSET);
  79
  80         if (value & BIT(IPROC_PWM_CTRL_EN_SHIFT(pwm->hwpwm)))
  81                 state->enabled = true;
  82         else
  83                 state->enabled = false;
  84
  85         if (value & BIT(IPROC_PWM_CTRL_POLARITY_SHIFT(pwm->hwpwm)))
  86                 state->polarity = PWM_POLARITY_NORMAL;
  87         else
  88                 state->polarity = PWM_POLARITY_INVERSED;
  89
  90         rate = clk_get_rate(ip->clk);
  91         if (rate == 0) {
  92                 state->period = 0;
  93                 state->duty_cycle = 0;
  94                 return 0;
  95         }
  96
  97         value = readl(ip->base + IPROC_PWM_PRESCALE_OFFSET);
  98         prescale = value >> IPROC_PWM_PRESCALE_SHIFT(pwm->hwpwm);
  99         prescale &= IPROC_PWM_PRESCALE_MAX;
 100
 101         multi = NSEC_PER_SEC * (prescale + 1);
 102
 103         value = readl(ip->base + IPROC_PWM_PERIOD_OFFSET(pwm->hwpwm));
 104         tmp = (value & IPROC_PWM_PERIOD_MAX) * multi;
 105         state->period = div64_u64(tmp, rate);
 106
 107         value = readl(ip->base + IPROC_PWM_DUTY_CYCLE_OFFSET(pwm->hwpwm));
 108         tmp = (value & IPROC_PWM_PERIOD_MAX) * multi;
 109         state->duty_cycle = div64_u64(tmp, rate);
 110
 111         return 0;
 112 }
 113
 114 static int iproc_pwmc_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 115                             const struct pwm_state *state)
 116 {
 117         unsigned long prescale = IPROC_PWM_PRESCALE_MIN;
 118         struct iproc_pwmc *ip = to_iproc_pwmc(chip);
 119         u32 value, period, duty;
 120         u64 rate;
 121
 122         rate = clk_get_rate(ip->clk);
 123
 124         /*
 125          * Find period count, duty count and prescale to suit duty_cycle and
 126          * period. This is done according to formulas described below:
 127          *
 128          * period_ns = 10^9 * (PRESCALE + 1) * PC / PWM_CLK_RATE
 129          * duty_ns = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE
 130          *
 131          * PC = (PWM_CLK_RATE * period_ns) / (10^9 * (PRESCALE + 1))
 132          * DC = (PWM_CLK_RATE * duty_ns) / (10^9 * (PRESCALE + 1))
 133          */
 134         while (1) {
 135                 u64 value, div;
 136
 137                 div = NSEC_PER_SEC * (prescale + 1);
 138                 value = rate * state->period;
 139                 period = div64_u64(value, div);
 140                 value = rate * state->duty_cycle;
 141                 duty = div64_u64(value, div);
 142
 143                 if (period < IPROC_PWM_PERIOD_MIN)
 144                         return -EINVAL;
 145
 146                 if (period <= IPROC_PWM_PERIOD_MAX &&
 147                      duty <= IPROC_PWM_DUTY_CYCLE_MAX)
 148                         break;
 149
 150                 /* Otherwise, increase prescale and recalculate counts */
 151                 if (++prescale > IPROC_PWM_PRESCALE_MAX)
 152                         return -EINVAL;
 153         }
 154
 155         iproc_pwmc_disable(ip, pwm->hwpwm);
 156
 157         /* Set prescale */
 158         value = readl(ip->base + IPROC_PWM_PRESCALE_OFFSET);
 159         value &= ~IPROC_PWM_PRESCALE_MASK(pwm->hwpwm);
 160         value |= prescale << IPROC_PWM_PRESCALE_SHIFT(pwm->hwpwm);
 161         writel(value, ip->base + IPROC_PWM_PRESCALE_OFFSET);
 162
 163         /* set period and duty cycle */
 164         writel(period, ip->base + IPROC_PWM_PERIOD_OFFSET(pwm->hwpwm));
 165         writel(duty, ip->base + IPROC_PWM_DUTY_CYCLE_OFFSET(pwm->hwpwm));
 166
 167         /* set polarity */
 168         value = readl(ip->base + IPROC_PWM_CTRL_OFFSET);
 169
 170         if (state->polarity == PWM_POLARITY_NORMAL)
 171                 value |= 1 << IPROC_PWM_CTRL_POLARITY_SHIFT(pwm->hwpwm);
 172         else
 173                 value &= ~(1 << IPROC_PWM_CTRL_POLARITY_SHIFT(pwm->hwpwm));
 174
 175         writel(value, ip->base + IPROC_PWM_CTRL_OFFSET);
 176
 177         if (state->enabled)
 178                 iproc_pwmc_enable(ip, pwm->hwpwm);
 179
 180         return 0;
 181 }
 182
 183 static const struct pwm_ops iproc_pwm_ops = {
 184         .apply = iproc_pwmc_apply,
 185         .get_state = iproc_pwmc_get_state,
 186 };
 187
 188 static int iproc_pwmc_probe(struct platform_device *pdev)
 189 {
 190         struct iproc_pwmc *ip;
 191         unsigned int i;
 192         u32 value;
 193         int ret;
 194
 195         ip = devm_kzalloc(&pdev->dev, sizeof(*ip), GFP_KERNEL);
 196         if (!ip)
 197                 return -ENOMEM;
 198
 199         platform_set_drvdata(pdev, ip);
 200
 201         ip->chip.dev = &pdev->dev;
 202         ip->chip.ops = &iproc_pwm_ops;
 203         ip->chip.npwm = 4;
 204
 205         ip->base = devm_platform_ioremap_resource(pdev, 0);
 206         if (IS_ERR(ip->base))
 207                 return PTR_ERR(ip->base);
 208
 209         ip->clk = devm_clk_get_enabled(&pdev->dev, NULL);
 210         if (IS_ERR(ip->clk))
 211                 return dev_err_probe(&pdev->dev, PTR_ERR(ip->clk),
 212                                      "failed to get clock\n");
 213
 214         /* Set full drive and normal polarity for all channels */
 215         value = readl(ip->base + IPROC_PWM_CTRL_OFFSET);
 216
 217         for (i = 0; i < ip->chip.npwm; i++) {
 218                 value &= ~(1 << IPROC_PWM_CTRL_TYPE_SHIFT(i));
 219                 value |= 1 << IPROC_PWM_CTRL_POLARITY_SHIFT(i);
 220         }
 221
 222         writel(value, ip->base + IPROC_PWM_CTRL_OFFSET);
 223
 224         ret = devm_pwmchip_add(&pdev->dev, &ip->chip);
 225         if (ret < 0)
 226                 return dev_err_probe(&pdev->dev, ret,
 227                                      "failed to add PWM chip\n");
 228
 229         return 0;
 230 }
 231
 232 static const struct of_device_id bcm_iproc_pwmc_dt[] = {
 233         { .compatible = "brcm,iproc-pwm" },
 234         { },
 235 };
 236 MODULE_DEVICE_TABLE(of, bcm_iproc_pwmc_dt);
 237
 238 static struct platform_driver iproc_pwmc_driver = {
 239         .driver = {
 240                 .name = "bcm-iproc-pwm",
 241                 .of_match_table = bcm_iproc_pwmc_dt,
 242         },
 243         .probe = iproc_pwmc_probe,
 244 };
 245 module_platform_driver(iproc_pwmc_driver);
 246
 247 MODULE_AUTHOR("Yendapally Reddy Dhananjaya Reddy <yendapally.reddy@broadcom.com>");
 248 MODULE_DESCRIPTION("Broadcom iProc PWM driver");
 249 MODULE_LICENSE("GPL v2");