linux/drivers/pwm/pwm-bcm-iproc.c
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   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
  46struct iproc_pwmc {
  47        struct pwm_chip chip;
  48        void __iomem *base;
  49        struct clk *clk;
  50};
  51
  52static inline struct iproc_pwmc *to_iproc_pwmc(struct pwm_chip *chip)
  53{
  54        return container_of(chip, struct iproc_pwmc, chip);
  55}
  56
  57static 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
  69static 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
  81static 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
 122static 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
 191static 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
 197static 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
 250static 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
 261static const struct of_device_id bcm_iproc_pwmc_dt[] = {
 262        { .compatible = "brcm,iproc-pwm" },
 263        { },
 264};
 265MODULE_DEVICE_TABLE(of, bcm_iproc_pwmc_dt);
 266
 267static 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};
 275module_platform_driver(iproc_pwmc_driver);
 276
 277MODULE_AUTHOR("Yendapally Reddy Dhananjaya Reddy <yendapally.reddy@broadcom.com>");
 278MODULE_DESCRIPTION("Broadcom iProc PWM driver");
 279MODULE_LICENSE("GPL v2");
 280