drivers/pwm/pwm-rcar.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * R-Car PWM Timer driver
   4  *
   5  * Copyright (C) 2015 Renesas Electronics Corporation
   6  *
   7  * Limitations:
   8  * - The hardware cannot generate a 0% duty cycle.
   9  */
  10
  11 #include <linux/clk.h>
  12 #include <linux/err.h>
  13 #include <linux/io.h>
  14 #include <linux/log2.h>
  15 #include <linux/math64.h>
  16 #include <linux/module.h>
  17 #include <linux/of.h>
  18 #include <linux/platform_device.h>
  19 #include <linux/pm_runtime.h>
  20 #include <linux/pwm.h>
  21 #include <linux/slab.h>
  22
  23 #define RCAR_PWM_MAX_DIVISION   24
  24 #define RCAR_PWM_MAX_CYCLE      1023
  25
  26 #define RCAR_PWMCR              0x00
  27 #define  RCAR_PWMCR_CC0_MASK    0x000f0000
  28 #define  RCAR_PWMCR_CC0_SHIFT   16
  29 #define  RCAR_PWMCR_CCMD        BIT(15)
  30 #define  RCAR_PWMCR_SYNC        BIT(11)
  31 #define  RCAR_PWMCR_SS0         BIT(4)
  32 #define  RCAR_PWMCR_EN0         BIT(0)
  33
  34 #define RCAR_PWMCNT             0x04
  35 #define  RCAR_PWMCNT_CYC0_MASK  0x03ff0000
  36 #define  RCAR_PWMCNT_CYC0_SHIFT 16
  37 #define  RCAR_PWMCNT_PH0_MASK   0x000003ff
  38 #define  RCAR_PWMCNT_PH0_SHIFT  0
  39
  40 struct rcar_pwm_chip {
  41         void __iomem *base;
  42         struct clk *clk;
  43 };
  44
  45 static inline struct rcar_pwm_chip *to_rcar_pwm_chip(struct pwm_chip *chip)
  46 {
  47         return pwmchip_get_drvdata(chip);
  48 }
  49
  50 static void rcar_pwm_write(struct rcar_pwm_chip *rp, u32 data,
  51                            unsigned int offset)
  52 {
  53         writel(data, rp->base + offset);
  54 }
  55
  56 static u32 rcar_pwm_read(struct rcar_pwm_chip *rp, unsigned int offset)
  57 {
  58         return readl(rp->base + offset);
  59 }
  60
  61 static void rcar_pwm_update(struct rcar_pwm_chip *rp, u32 mask, u32 data,
  62                             unsigned int offset)
  63 {
  64         u32 value;
  65
  66         value = rcar_pwm_read(rp, offset);
  67         value &= ~mask;
  68         value |= data & mask;
  69         rcar_pwm_write(rp, value, offset);
  70 }
  71
  72 static int rcar_pwm_get_clock_division(struct rcar_pwm_chip *rp, int period_ns)
  73 {
  74         unsigned long clk_rate = clk_get_rate(rp->clk);
  75         u64 div, tmp;
  76
  77         if (clk_rate == 0)
  78                 return -EINVAL;
  79
  80         div = (u64)NSEC_PER_SEC * RCAR_PWM_MAX_CYCLE;
  81         tmp = (u64)period_ns * clk_rate + div - 1;
  82         tmp = div64_u64(tmp, div);
  83         div = ilog2(tmp - 1) + 1;
  84
  85         return (div <= RCAR_PWM_MAX_DIVISION) ? div : -ERANGE;
  86 }
  87
  88 static void rcar_pwm_set_clock_control(struct rcar_pwm_chip *rp,
  89                                        unsigned int div)
  90 {
  91         u32 value;
  92
  93         value = rcar_pwm_read(rp, RCAR_PWMCR);
  94         value &= ~(RCAR_PWMCR_CCMD | RCAR_PWMCR_CC0_MASK);
  95
  96         if (div & 1)
  97                 value |= RCAR_PWMCR_CCMD;
  98
  99         div >>= 1;
 100
 101         value |= div << RCAR_PWMCR_CC0_SHIFT;
 102         rcar_pwm_write(rp, value, RCAR_PWMCR);
 103 }
 104
 105 static int rcar_pwm_set_counter(struct rcar_pwm_chip *rp, int div, int duty_ns,
 106                                 int period_ns)
 107 {
 108         unsigned long long one_cycle, tmp;      /* 0.01 nanoseconds */
 109         unsigned long clk_rate = clk_get_rate(rp->clk);
 110         u32 cyc, ph;
 111
 112         one_cycle = NSEC_PER_SEC * 100ULL << div;
 113         do_div(one_cycle, clk_rate);
 114
 115         tmp = period_ns * 100ULL;
 116         do_div(tmp, one_cycle);
 117         cyc = (tmp << RCAR_PWMCNT_CYC0_SHIFT) & RCAR_PWMCNT_CYC0_MASK;
 118
 119         tmp = duty_ns * 100ULL;
 120         do_div(tmp, one_cycle);
 121         ph = tmp & RCAR_PWMCNT_PH0_MASK;
 122
 123         /* Avoid prohibited setting */
 124         if (cyc == 0 || ph == 0)
 125                 return -EINVAL;
 126
 127         rcar_pwm_write(rp, cyc | ph, RCAR_PWMCNT);
 128
 129         return 0;
 130 }
 131
 132 static int rcar_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
 133 {
 134         return pm_runtime_get_sync(pwmchip_parent(chip));
 135 }
 136
 137 static void rcar_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
 138 {
 139         pm_runtime_put(pwmchip_parent(chip));
 140 }
 141
 142 static int rcar_pwm_enable(struct rcar_pwm_chip *rp)
 143 {
 144         u32 value;
 145
 146         /* Don't enable the PWM device if CYC0 or PH0 is 0 */
 147         value = rcar_pwm_read(rp, RCAR_PWMCNT);
 148         if ((value & RCAR_PWMCNT_CYC0_MASK) == 0 ||
 149             (value & RCAR_PWMCNT_PH0_MASK) == 0)
 150                 return -EINVAL;
 151
 152         rcar_pwm_update(rp, RCAR_PWMCR_EN0, RCAR_PWMCR_EN0, RCAR_PWMCR);
 153
 154         return 0;
 155 }
 156
 157 static void rcar_pwm_disable(struct rcar_pwm_chip *rp)
 158 {
 159         rcar_pwm_update(rp, RCAR_PWMCR_EN0, 0, RCAR_PWMCR);
 160 }
 161
 162 static int rcar_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 163                           const struct pwm_state *state)
 164 {
 165         struct rcar_pwm_chip *rp = to_rcar_pwm_chip(chip);
 166         int div, ret;
 167
 168         /* This HW/driver only supports normal polarity */
 169         if (state->polarity != PWM_POLARITY_NORMAL)
 170                 return -EINVAL;
 171
 172         if (!state->enabled) {
 173                 rcar_pwm_disable(rp);
 174                 return 0;
 175         }
 176
 177         div = rcar_pwm_get_clock_division(rp, state->period);
 178         if (div < 0)
 179                 return div;
 180
 181         rcar_pwm_update(rp, RCAR_PWMCR_SYNC, RCAR_PWMCR_SYNC, RCAR_PWMCR);
 182
 183         ret = rcar_pwm_set_counter(rp, div, state->duty_cycle, state->period);
 184         if (!ret)
 185                 rcar_pwm_set_clock_control(rp, div);
 186
 187         /* The SYNC should be set to 0 even if rcar_pwm_set_counter failed */
 188         rcar_pwm_update(rp, RCAR_PWMCR_SYNC, 0, RCAR_PWMCR);
 189
 190         if (!ret)
 191                 ret = rcar_pwm_enable(rp);
 192
 193         return ret;
 194 }
 195
 196 static const struct pwm_ops rcar_pwm_ops = {
 197         .request = rcar_pwm_request,
 198         .free = rcar_pwm_free,
 199         .apply = rcar_pwm_apply,
 200 };
 201
 202 static int rcar_pwm_probe(struct platform_device *pdev)
 203 {
 204         struct pwm_chip *chip;
 205         struct rcar_pwm_chip *rcar_pwm;
 206         int ret;
 207
 208         chip = devm_pwmchip_alloc(&pdev->dev, 1, sizeof(*rcar_pwm));
 209         if (IS_ERR(chip))
 210                 return PTR_ERR(chip);
 211         rcar_pwm = to_rcar_pwm_chip(chip);
 212
 213         rcar_pwm->base = devm_platform_ioremap_resource(pdev, 0);
 214         if (IS_ERR(rcar_pwm->base))
 215                 return PTR_ERR(rcar_pwm->base);
 216
 217         rcar_pwm->clk = devm_clk_get(&pdev->dev, NULL);
 218         if (IS_ERR(rcar_pwm->clk)) {
 219                 dev_err(&pdev->dev, "cannot get clock\n");
 220                 return PTR_ERR(rcar_pwm->clk);
 221         }
 222
 223         chip->ops = &rcar_pwm_ops;
 224
 225         platform_set_drvdata(pdev, chip);
 226
 227         pm_runtime_enable(&pdev->dev);
 228
 229         ret = pwmchip_add(chip);
 230         if (ret < 0) {
 231                 dev_err(&pdev->dev, "failed to register PWM chip: %d\n", ret);
 232                 pm_runtime_disable(&pdev->dev);
 233                 return ret;
 234         }
 235
 236         return 0;
 237 }
 238
 239 static void rcar_pwm_remove(struct platform_device *pdev)
 240 {
 241         struct pwm_chip *chip = platform_get_drvdata(pdev);
 242
 243         pwmchip_remove(chip);
 244
 245         pm_runtime_disable(&pdev->dev);
 246 }
 247
 248 static const struct of_device_id rcar_pwm_of_table[] = {
 249         { .compatible = "renesas,pwm-rcar", },
 250         { },
 251 };
 252 MODULE_DEVICE_TABLE(of, rcar_pwm_of_table);
 253
 254 static struct platform_driver rcar_pwm_driver = {
 255         .probe = rcar_pwm_probe,
 256         .remove_new = rcar_pwm_remove,
 257         .driver = {
 258                 .name = "pwm-rcar",
 259                 .of_match_table = rcar_pwm_of_table,
 260         }
 261 };
 262 module_platform_driver(rcar_pwm_driver);
 263
 264 MODULE_AUTHOR("Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>");
 265 MODULE_DESCRIPTION("Renesas PWM Timer Driver");
 266 MODULE_LICENSE("GPL v2");
 267 MODULE_ALIAS("platform:pwm-rcar");