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        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
 117static int iproc_pwmc_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 118                            const 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
 187static 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
 193static 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
 251static 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
 260static const struct of_device_id bcm_iproc_pwmc_dt[] = {
 261        { .compatible = "brcm,iproc-pwm" },
 262        { },
 263};
 264MODULE_DEVICE_TABLE(of, bcm_iproc_pwmc_dt);
 265
 266static 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};
 274module_platform_driver(iproc_pwmc_driver);
 275
 276MODULE_AUTHOR("Yendapally Reddy Dhananjaya Reddy <yendapally.reddy@broadcom.com>");
 277MODULE_DESCRIPTION("Broadcom iProc PWM driver");
 278MODULE_LICENSE("GPL v2");
 279