drivers/pwm/pwm-bcm-iproc.c

   1 /*
   2  * Copyright (C) 2016 Broadcom
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License as
   6  * published by the Free Software Foundation version 2.
   7  *
   8  * This program is distributed "as is" WITHOUT ANY WARRANTY of any
   9  * kind, whether express or implied; without even the implied warranty
  10  * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  */
  13
  14 #include <linux/clk.h>
  15 #include <linux/delay.h>
  16 #include <linux/err.h>
  17 #include <linux/io.h>
  18 #include <linux/math64.h>
  19 #include <linux/module.h>
  20 #include <linux/of.h>
  21 #include <linux/platform_device.h>
  22 #include <linux/pwm.h>
  23
  24 #define IPROC_PWM_CTRL_OFFSET                   0x00
  25 #define IPROC_PWM_CTRL_TYPE_SHIFT(ch)           (15 + (ch))
  26 #define IPROC_PWM_CTRL_POLARITY_SHIFT(ch)       (8 + (ch))
  27 #define IPROC_PWM_CTRL_EN_SHIFT(ch)             (ch)
  28
  29 #define IPROC_PWM_PERIOD_OFFSET(ch)             (0x04 + ((ch) << 3))
  30 #define IPROC_PWM_PERIOD_MIN                    0x02
  31 #define IPROC_PWM_PERIOD_MAX                    0xffff
  32
  33 #define IPROC_PWM_DUTY_CYCLE_OFFSET(ch)         (0x08 + ((ch) << 3))
  34 #define IPROC_PWM_DUTY_CYCLE_MIN                0x00
  35 #define IPROC_PWM_DUTY_CYCLE_MAX                0xffff
  36
  37 #define IPROC_PWM_PRESCALE_OFFSET               0x24
  38 #define IPROC_PWM_PRESCALE_BITS                 0x06
  39 #define IPROC_PWM_PRESCALE_SHIFT(ch)            ((3 - (ch)) * \
  40                                                  IPROC_PWM_PRESCALE_BITS)
  41 #define IPROC_PWM_PRESCALE_MASK(ch)             (IPROC_PWM_PRESCALE_MAX << \
  42                                                  IPROC_PWM_PRESCALE_SHIFT(ch))
  43 #define IPROC_PWM_PRESCALE_MIN                  0x00
  44 #define IPROC_PWM_PRESCALE_MAX                  0x3f
  45
  46 struct iproc_pwmc {
  47         struct pwm_chip chip;
  48         void __iomem *base;
  49         struct clk *clk;
  50 };
  51
  52 static inline struct iproc_pwmc *to_iproc_pwmc(struct pwm_chip *chip)
  53 {
  54         return container_of(chip, struct iproc_pwmc, chip);
  55 }
  56
  57 static void iproc_pwmc_enable(struct iproc_pwmc *ip, unsigned int channel)
  58 {
  59         u32 value;
  60
  61         value = readl(ip->base + IPROC_PWM_CTRL_OFFSET);
  62         value |= 1 << IPROC_PWM_CTRL_EN_SHIFT(channel);
  63         writel(value, ip->base + IPROC_PWM_CTRL_OFFSET);
  64
  65         /* must be a 400 ns delay between clearing and setting enable bit */
  66         ndelay(400);
  67 }
  68
  69 static void iproc_pwmc_disable(struct iproc_pwmc *ip, unsigned int channel)
  70 {
  71         u32 value;
  72
  73         value = readl(ip->base + IPROC_PWM_CTRL_OFFSET);
  74         value &= ~(1 << IPROC_PWM_CTRL_EN_SHIFT(channel));
  75         writel(value, ip->base + IPROC_PWM_CTRL_OFFSET);
  76
  77         /* must be a 400 ns delay between clearing and setting enable bit */
  78         ndelay(400);
  79 }
  80
  81 static void iproc_pwmc_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
  82                                  struct pwm_state *state)
  83 {
  84         struct iproc_pwmc *ip = to_iproc_pwmc(chip);
  85         u64 tmp, multi, rate;
  86         u32 value, prescale;
  87
  88         rate = clk_get_rate(ip->clk);
  89
  90         value = readl(ip->base + IPROC_PWM_CTRL_OFFSET);
  91
  92         if (value & BIT(IPROC_PWM_CTRL_EN_SHIFT(pwm->hwpwm)))
  93                 state->enabled = true;
  94         else
  95                 state->enabled = false;
  96
  97         if (value & BIT(IPROC_PWM_CTRL_POLARITY_SHIFT(pwm->hwpwm)))
  98                 state->polarity = PWM_POLARITY_NORMAL;
  99         else
 100                 state->polarity = PWM_POLARITY_INVERSED;
 101
 102         value = readl(ip->base + IPROC_PWM_PRESCALE_OFFSET);
 103         prescale = value >> IPROC_PWM_PRESCALE_SHIFT(pwm->hwpwm);
 104         prescale &= IPROC_PWM_PRESCALE_MAX;
 105
 106         multi = NSEC_PER_SEC * (prescale + 1);
 107
 108         value = readl(ip->base + IPROC_PWM_PERIOD_OFFSET(pwm->hwpwm));
 109         tmp = (value & IPROC_PWM_PERIOD_MAX) * multi;
 110         state->period = div64_u64(tmp, rate);
 111
 112         value = readl(ip->base + IPROC_PWM_DUTY_CYCLE_OFFSET(pwm->hwpwm));
 113         tmp = (value & IPROC_PWM_PERIOD_MAX) * multi;
 114         state->duty_cycle = div64_u64(tmp, rate);
 115 }
 116
 117 static int iproc_pwmc_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 118                             struct pwm_state *state)
 119 {
 120         unsigned long prescale = IPROC_PWM_PRESCALE_MIN;
 121         struct iproc_pwmc *ip = to_iproc_pwmc(chip);
 122         u32 value, period, duty;
 123         u64 rate;
 124
 125         rate = clk_get_rate(ip->clk);
 126
 127         /*
 128          * Find period count, duty count and prescale to suit duty_cycle and
 129          * period. This is done according to formulas described below:
 130          *
 131          * period_ns = 10^9 * (PRESCALE + 1) * PC / PWM_CLK_RATE
 132          * duty_ns = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE
 133          *
 134          * PC = (PWM_CLK_RATE * period_ns) / (10^9 * (PRESCALE + 1))
 135          * DC = (PWM_CLK_RATE * duty_ns) / (10^9 * (PRESCALE + 1))
 136          */
 137         while (1) {
 138                 u64 value, div;
 139
 140                 div = NSEC_PER_SEC * (prescale + 1);
 141                 value = rate * state->period;
 142                 period = div64_u64(value, div);
 143                 value = rate * state->duty_cycle;
 144                 duty = div64_u64(value, div);
 145
 146                 if (period < IPROC_PWM_PERIOD_MIN ||
 147                     duty < IPROC_PWM_DUTY_CYCLE_MIN)
 148                         return -EINVAL;
 149
 150                 if (period <= IPROC_PWM_PERIOD_MAX &&
 151                      duty <= IPROC_PWM_DUTY_CYCLE_MAX)
 152                         break;
 153
 154                 /* Otherwise, increase prescale and recalculate counts */
 155                 if (++prescale > IPROC_PWM_PRESCALE_MAX)
 156                         return -EINVAL;
 157         }
 158
 159         iproc_pwmc_disable(ip, pwm->hwpwm);
 160
 161         /* Set prescale */
 162         value = readl(ip->base + IPROC_PWM_PRESCALE_OFFSET);
 163         value &= ~IPROC_PWM_PRESCALE_MASK(pwm->hwpwm);
 164         value |= prescale << IPROC_PWM_PRESCALE_SHIFT(pwm->hwpwm);
 165         writel(value, ip->base + IPROC_PWM_PRESCALE_OFFSET);
 166
 167         /* set period and duty cycle */
 168         writel(period, ip->base + IPROC_PWM_PERIOD_OFFSET(pwm->hwpwm));
 169         writel(duty, ip->base + IPROC_PWM_DUTY_CYCLE_OFFSET(pwm->hwpwm));
 170
 171         /* set polarity */
 172         value = readl(ip->base + IPROC_PWM_CTRL_OFFSET);
 173
 174         if (state->polarity == PWM_POLARITY_NORMAL)
 175                 value |= 1 << IPROC_PWM_CTRL_POLARITY_SHIFT(pwm->hwpwm);
 176         else
 177                 value &= ~(1 << IPROC_PWM_CTRL_POLARITY_SHIFT(pwm->hwpwm));
 178
 179         writel(value, ip->base + IPROC_PWM_CTRL_OFFSET);
 180
 181         if (state->enabled)
 182                 iproc_pwmc_enable(ip, pwm->hwpwm);
 183
 184         return 0;
 185 }
 186
 187 static const struct pwm_ops iproc_pwm_ops = {
 188         .apply = iproc_pwmc_apply,
 189         .get_state = iproc_pwmc_get_state,
 190         .owner = THIS_MODULE,
 191 };
 192
 193 static int iproc_pwmc_probe(struct platform_device *pdev)
 194 {
 195         struct iproc_pwmc *ip;
 196         struct resource *res;
 197         unsigned int i;
 198         u32 value;
 199         int ret;
 200
 201         ip = devm_kzalloc(&pdev->dev, sizeof(*ip), GFP_KERNEL);
 202         if (!ip)
 203                 return -ENOMEM;
 204
 205         platform_set_drvdata(pdev, ip);
 206
 207         ip->chip.dev = &pdev->dev;
 208         ip->chip.ops = &iproc_pwm_ops;
 209         ip->chip.base = -1;
 210         ip->chip.npwm = 4;
 211         ip->chip.of_xlate = of_pwm_xlate_with_flags;
 212         ip->chip.of_pwm_n_cells = 3;
 213
 214         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 215         ip->base = devm_ioremap_resource(&pdev->dev, res);
 216         if (IS_ERR(ip->base))
 217                 return PTR_ERR(ip->base);
 218
 219         ip->clk = devm_clk_get(&pdev->dev, NULL);
 220         if (IS_ERR(ip->clk)) {
 221                 dev_err(&pdev->dev, "failed to get clock: %ld\n",
 222                         PTR_ERR(ip->clk));
 223                 return PTR_ERR(ip->clk);
 224         }
 225
 226         ret = clk_prepare_enable(ip->clk);
 227         if (ret < 0) {
 228                 dev_err(&pdev->dev, "failed to enable clock: %d\n", ret);
 229                 return ret;
 230         }
 231
 232         /* Set full drive and normal polarity for all channels */
 233         value = readl(ip->base + IPROC_PWM_CTRL_OFFSET);
 234
 235         for (i = 0; i < ip->chip.npwm; i++) {
 236                 value &= ~(1 << IPROC_PWM_CTRL_TYPE_SHIFT(i));
 237                 value |= 1 << IPROC_PWM_CTRL_POLARITY_SHIFT(i);
 238         }
 239
 240         writel(value, ip->base + IPROC_PWM_CTRL_OFFSET);
 241
 242         ret = pwmchip_add(&ip->chip);
 243         if (ret < 0) {
 244                 dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret);
 245                 clk_disable_unprepare(ip->clk);
 246         }
 247
 248         return ret;
 249 }
 250
 251 static int iproc_pwmc_remove(struct platform_device *pdev)
 252 {
 253         struct iproc_pwmc *ip = platform_get_drvdata(pdev);
 254
 255         clk_disable_unprepare(ip->clk);
 256
 257         return pwmchip_remove(&ip->chip);
 258 }
 259
 260 static const struct of_device_id bcm_iproc_pwmc_dt[] = {
 261         { .compatible = "brcm,iproc-pwm" },
 262         { },
 263 };
 264 MODULE_DEVICE_TABLE(of, bcm_iproc_pwmc_dt);
 265
 266 static struct platform_driver iproc_pwmc_driver = {
 267         .driver = {
 268                 .name = "bcm-iproc-pwm",
 269                 .of_match_table = bcm_iproc_pwmc_dt,
 270         },
 271         .probe = iproc_pwmc_probe,
 272         .remove = iproc_pwmc_remove,
 273 };
 274 module_platform_driver(iproc_pwmc_driver);
 275
 276 MODULE_AUTHOR("Yendapally Reddy Dhananjaya Reddy <yendapally.reddy@broadcom.com>");
 277 MODULE_DESCRIPTION("Broadcom iProc PWM driver");
 278 MODULE_LICENSE("GPL v2");