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         value = readl(ip->base + IPROC_PWM_CTRL_OFFSET);
  89
  90         if (value & BIT(IPROC_PWM_CTRL_EN_SHIFT(pwm->hwpwm)))
  91                 state->enabled = true;
  92         else
  93                 state->enabled = false;
  94
  95         if (value & BIT(IPROC_PWM_CTRL_POLARITY_SHIFT(pwm->hwpwm)))
  96                 state->polarity = PWM_POLARITY_NORMAL;
  97         else
  98                 state->polarity = PWM_POLARITY_INVERSED;
  99
 100         rate = clk_get_rate(ip->clk);
 101         if (rate == 0) {
 102                 state->period = 0;
 103                 state->duty_cycle = 0;
 104                 return;
 105         }
 106
 107         value = readl(ip->base + IPROC_PWM_PRESCALE_OFFSET);
 108         prescale = value >> IPROC_PWM_PRESCALE_SHIFT(pwm->hwpwm);
 109         prescale &= IPROC_PWM_PRESCALE_MAX;
 110
 111         multi = NSEC_PER_SEC * (prescale + 1);
 112
 113         value = readl(ip->base + IPROC_PWM_PERIOD_OFFSET(pwm->hwpwm));
 114         tmp = (value & IPROC_PWM_PERIOD_MAX) * multi;
 115         state->period = div64_u64(tmp, rate);
 116
 117         value = readl(ip->base + IPROC_PWM_DUTY_CYCLE_OFFSET(pwm->hwpwm));
 118         tmp = (value & IPROC_PWM_PERIOD_MAX) * multi;
 119         state->duty_cycle = div64_u64(tmp, rate);
 120 }
 121
 122 static int iproc_pwmc_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 123                             const struct pwm_state *state)
 124 {
 125         unsigned long prescale = IPROC_PWM_PRESCALE_MIN;
 126         struct iproc_pwmc *ip = to_iproc_pwmc(chip);
 127         u32 value, period, duty;
 128         u64 rate;
 129
 130         rate = clk_get_rate(ip->clk);
 131
 132         /*
 133          * Find period count, duty count and prescale to suit duty_cycle and
 134          * period. This is done according to formulas described below:
 135          *
 136          * period_ns = 10^9 * (PRESCALE + 1) * PC / PWM_CLK_RATE
 137          * duty_ns = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE
 138          *
 139          * PC = (PWM_CLK_RATE * period_ns) / (10^9 * (PRESCALE + 1))
 140          * DC = (PWM_CLK_RATE * duty_ns) / (10^9 * (PRESCALE + 1))
 141          */
 142         while (1) {
 143                 u64 value, div;
 144
 145                 div = NSEC_PER_SEC * (prescale + 1);
 146                 value = rate * state->period;
 147                 period = div64_u64(value, div);
 148                 value = rate * state->duty_cycle;
 149                 duty = div64_u64(value, div);
 150
 151                 if (period < IPROC_PWM_PERIOD_MIN)
 152                         return -EINVAL;
 153
 154                 if (period <= IPROC_PWM_PERIOD_MAX &&
 155                      duty <= IPROC_PWM_DUTY_CYCLE_MAX)
 156                         break;
 157
 158                 /* Otherwise, increase prescale and recalculate counts */
 159                 if (++prescale > IPROC_PWM_PRESCALE_MAX)
 160                         return -EINVAL;
 161         }
 162
 163         iproc_pwmc_disable(ip, pwm->hwpwm);
 164
 165         /* Set prescale */
 166         value = readl(ip->base + IPROC_PWM_PRESCALE_OFFSET);
 167         value &= ~IPROC_PWM_PRESCALE_MASK(pwm->hwpwm);
 168         value |= prescale << IPROC_PWM_PRESCALE_SHIFT(pwm->hwpwm);
 169         writel(value, ip->base + IPROC_PWM_PRESCALE_OFFSET);
 170
 171         /* set period and duty cycle */
 172         writel(period, ip->base + IPROC_PWM_PERIOD_OFFSET(pwm->hwpwm));
 173         writel(duty, ip->base + IPROC_PWM_DUTY_CYCLE_OFFSET(pwm->hwpwm));
 174
 175         /* set polarity */
 176         value = readl(ip->base + IPROC_PWM_CTRL_OFFSET);
 177
 178         if (state->polarity == PWM_POLARITY_NORMAL)
 179                 value |= 1 << IPROC_PWM_CTRL_POLARITY_SHIFT(pwm->hwpwm);
 180         else
 181                 value &= ~(1 << IPROC_PWM_CTRL_POLARITY_SHIFT(pwm->hwpwm));
 182
 183         writel(value, ip->base + IPROC_PWM_CTRL_OFFSET);
 184
 185         if (state->enabled)
 186                 iproc_pwmc_enable(ip, pwm->hwpwm);
 187
 188         return 0;
 189 }
 190
 191 static const struct pwm_ops iproc_pwm_ops = {
 192         .apply = iproc_pwmc_apply,
 193         .get_state = iproc_pwmc_get_state,
 194         .owner = THIS_MODULE,
 195 };
 196
 197 static int iproc_pwmc_probe(struct platform_device *pdev)
 198 {
 199         struct iproc_pwmc *ip;
 200         unsigned int i;
 201         u32 value;
 202         int ret;
 203
 204         ip = devm_kzalloc(&pdev->dev, sizeof(*ip), GFP_KERNEL);
 205         if (!ip)
 206                 return -ENOMEM;
 207
 208         platform_set_drvdata(pdev, ip);
 209
 210         ip->chip.dev = &pdev->dev;
 211         ip->chip.ops = &iproc_pwm_ops;
 212         ip->chip.npwm = 4;
 213
 214         ip->base = devm_platform_ioremap_resource(pdev, 0);
 215         if (IS_ERR(ip->base))
 216                 return PTR_ERR(ip->base);
 217
 218         ip->clk = devm_clk_get(&pdev->dev, NULL);
 219         if (IS_ERR(ip->clk)) {
 220                 dev_err(&pdev->dev, "failed to get clock: %ld\n",
 221                         PTR_ERR(ip->clk));
 222                 return PTR_ERR(ip->clk);
 223         }
 224
 225         ret = clk_prepare_enable(ip->clk);
 226         if (ret < 0) {
 227                 dev_err(&pdev->dev, "failed to enable clock: %d\n", ret);
 228                 return ret;
 229         }
 230
 231         /* Set full drive and normal polarity for all channels */
 232         value = readl(ip->base + IPROC_PWM_CTRL_OFFSET);
 233
 234         for (i = 0; i < ip->chip.npwm; i++) {
 235                 value &= ~(1 << IPROC_PWM_CTRL_TYPE_SHIFT(i));
 236                 value |= 1 << IPROC_PWM_CTRL_POLARITY_SHIFT(i);
 237         }
 238
 239         writel(value, ip->base + IPROC_PWM_CTRL_OFFSET);
 240
 241         ret = pwmchip_add(&ip->chip);
 242         if (ret < 0) {
 243                 dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret);
 244                 clk_disable_unprepare(ip->clk);
 245         }
 246
 247         return ret;
 248 }
 249
 250 static int iproc_pwmc_remove(struct platform_device *pdev)
 251 {
 252         struct iproc_pwmc *ip = platform_get_drvdata(pdev);
 253
 254         pwmchip_remove(&ip->chip);
 255
 256         clk_disable_unprepare(ip->clk);
 257
 258         return 0;
 259 }
 260
 261 static const struct of_device_id bcm_iproc_pwmc_dt[] = {
 262         { .compatible = "brcm,iproc-pwm" },
 263         { },
 264 };
 265 MODULE_DEVICE_TABLE(of, bcm_iproc_pwmc_dt);
 266
 267 static struct platform_driver iproc_pwmc_driver = {
 268         .driver = {
 269                 .name = "bcm-iproc-pwm",
 270                 .of_match_table = bcm_iproc_pwmc_dt,
 271         },
 272         .probe = iproc_pwmc_probe,
 273         .remove = iproc_pwmc_remove,
 274 };
 275 module_platform_driver(iproc_pwmc_driver);
 276
 277 MODULE_AUTHOR("Yendapally Reddy Dhananjaya Reddy <yendapally.reddy@broadcom.com>");
 278 MODULE_DESCRIPTION("Broadcom iProc PWM driver");
 279 MODULE_LICENSE("GPL v2");