drivers/pwm/pwm-zx.c

   1 /*
   2  * Copyright (C) 2017 Sanechips Technology Co., Ltd.
   3  * Copyright 2017 Linaro Ltd.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation.
   8  */
   9
  10 #include <linux/clk.h>
  11 #include <linux/err.h>
  12 #include <linux/io.h>
  13 #include <linux/kernel.h>
  14 #include <linux/module.h>
  15 #include <linux/platform_device.h>
  16 #include <linux/pwm.h>
  17 #include <linux/slab.h>
  18
  19 #define ZX_PWM_MODE             0x0
  20 #define ZX_PWM_CLKDIV_SHIFT     2
  21 #define ZX_PWM_CLKDIV_MASK      GENMASK(11, 2)
  22 #define ZX_PWM_CLKDIV(x)        (((x) << ZX_PWM_CLKDIV_SHIFT) & \
  23                                          ZX_PWM_CLKDIV_MASK)
  24 #define ZX_PWM_POLAR            BIT(1)
  25 #define ZX_PWM_EN               BIT(0)
  26 #define ZX_PWM_PERIOD           0x4
  27 #define ZX_PWM_DUTY             0x8
  28
  29 #define ZX_PWM_CLKDIV_MAX       1023
  30 #define ZX_PWM_PERIOD_MAX       65535
  31
  32 struct zx_pwm_chip {
  33         struct pwm_chip chip;
  34         struct clk *pclk;
  35         struct clk *wclk;
  36         void __iomem *base;
  37 };
  38
  39 static inline struct zx_pwm_chip *to_zx_pwm_chip(struct pwm_chip *chip)
  40 {
  41         return container_of(chip, struct zx_pwm_chip, chip);
  42 }
  43
  44 static inline u32 zx_pwm_readl(struct zx_pwm_chip *zpc, unsigned int hwpwm,
  45                                unsigned int offset)
  46 {
  47         return readl(zpc->base + (hwpwm + 1) * 0x10 + offset);
  48 }
  49
  50 static inline void zx_pwm_writel(struct zx_pwm_chip *zpc, unsigned int hwpwm,
  51                                  unsigned int offset, u32 value)
  52 {
  53         writel(value, zpc->base + (hwpwm + 1) * 0x10 + offset);
  54 }
  55
  56 static void zx_pwm_set_mask(struct zx_pwm_chip *zpc, unsigned int hwpwm,
  57                             unsigned int offset, u32 mask, u32 value)
  58 {
  59         u32 data;
  60
  61         data = zx_pwm_readl(zpc, hwpwm, offset);
  62         data &= ~mask;
  63         data |= value & mask;
  64         zx_pwm_writel(zpc, hwpwm, offset, data);
  65 }
  66
  67 static void zx_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
  68                              struct pwm_state *state)
  69 {
  70         struct zx_pwm_chip *zpc = to_zx_pwm_chip(chip);
  71         unsigned long rate;
  72         unsigned int div;
  73         u32 value;
  74         u64 tmp;
  75
  76         value = zx_pwm_readl(zpc, pwm->hwpwm, ZX_PWM_MODE);
  77
  78         if (value & ZX_PWM_POLAR)
  79                 state->polarity = PWM_POLARITY_NORMAL;
  80         else
  81                 state->polarity = PWM_POLARITY_INVERSED;
  82
  83         if (value & ZX_PWM_EN)
  84                 state->enabled = true;
  85         else
  86                 state->enabled = false;
  87
  88         div = (value & ZX_PWM_CLKDIV_MASK) >> ZX_PWM_CLKDIV_SHIFT;
  89         rate = clk_get_rate(zpc->wclk);
  90
  91         tmp = zx_pwm_readl(zpc, pwm->hwpwm, ZX_PWM_PERIOD);
  92         tmp *= div * NSEC_PER_SEC;
  93         state->period = DIV_ROUND_CLOSEST_ULL(tmp, rate);
  94
  95         tmp = zx_pwm_readl(zpc, pwm->hwpwm, ZX_PWM_DUTY);
  96         tmp *= div * NSEC_PER_SEC;
  97         state->duty_cycle = DIV_ROUND_CLOSEST_ULL(tmp, rate);
  98 }
  99
 100 static int zx_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 101                          unsigned int duty_ns, unsigned int period_ns)
 102 {
 103         struct zx_pwm_chip *zpc = to_zx_pwm_chip(chip);
 104         unsigned int period_cycles, duty_cycles;
 105         unsigned long long c;
 106         unsigned int div = 1;
 107         unsigned long rate;
 108
 109         /* Find out the best divider */
 110         rate = clk_get_rate(zpc->wclk);
 111
 112         while (1) {
 113                 c = rate / div;
 114                 c = c * period_ns;
 115                 do_div(c, NSEC_PER_SEC);
 116
 117                 if (c < ZX_PWM_PERIOD_MAX)
 118                         break;
 119
 120                 div++;
 121
 122                 if (div > ZX_PWM_CLKDIV_MAX)
 123                         return -ERANGE;
 124         }
 125
 126         /* Calculate duty cycles */
 127         period_cycles = c;
 128         c *= duty_ns;
 129         do_div(c, period_ns);
 130         duty_cycles = c;
 131
 132         /*
 133          * If the PWM is being enabled, we have to temporarily disable it
 134          * before configuring the registers.
 135          */
 136         if (pwm_is_enabled(pwm))
 137                 zx_pwm_set_mask(zpc, pwm->hwpwm, ZX_PWM_MODE, ZX_PWM_EN, 0);
 138
 139         /* Set up registers */
 140         zx_pwm_set_mask(zpc, pwm->hwpwm, ZX_PWM_MODE, ZX_PWM_CLKDIV_MASK,
 141                         ZX_PWM_CLKDIV(div));
 142         zx_pwm_writel(zpc, pwm->hwpwm, ZX_PWM_PERIOD, period_cycles);
 143         zx_pwm_writel(zpc, pwm->hwpwm, ZX_PWM_DUTY, duty_cycles);
 144
 145         /* Re-enable the PWM if needed */
 146         if (pwm_is_enabled(pwm))
 147                 zx_pwm_set_mask(zpc, pwm->hwpwm, ZX_PWM_MODE,
 148                                 ZX_PWM_EN, ZX_PWM_EN);
 149
 150         return 0;
 151 }
 152
 153 static int zx_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 154                         struct pwm_state *state)
 155 {
 156         struct zx_pwm_chip *zpc = to_zx_pwm_chip(chip);
 157         struct pwm_state cstate;
 158         int ret;
 159
 160         pwm_get_state(pwm, &cstate);
 161
 162         if (state->polarity != cstate.polarity)
 163                 zx_pwm_set_mask(zpc, pwm->hwpwm, ZX_PWM_MODE, ZX_PWM_POLAR,
 164                                 (state->polarity == PWM_POLARITY_INVERSED) ?
 165                                  0 : ZX_PWM_POLAR);
 166
 167         if (state->period != cstate.period ||
 168             state->duty_cycle != cstate.duty_cycle) {
 169                 ret = zx_pwm_config(chip, pwm, state->duty_cycle,
 170                                     state->period);
 171                 if (ret)
 172                         return ret;
 173         }
 174
 175         if (state->enabled != cstate.enabled) {
 176                 if (state->enabled) {
 177                         ret = clk_prepare_enable(zpc->wclk);
 178                         if (ret)
 179                                 return ret;
 180
 181                         zx_pwm_set_mask(zpc, pwm->hwpwm, ZX_PWM_MODE,
 182                                         ZX_PWM_EN, ZX_PWM_EN);
 183                 } else {
 184                         zx_pwm_set_mask(zpc, pwm->hwpwm, ZX_PWM_MODE,
 185                                         ZX_PWM_EN, 0);
 186                         clk_disable_unprepare(zpc->wclk);
 187                 }
 188         }
 189
 190         return 0;
 191 }
 192
 193 static const struct pwm_ops zx_pwm_ops = {
 194         .apply = zx_pwm_apply,
 195         .get_state = zx_pwm_get_state,
 196         .owner = THIS_MODULE,
 197 };
 198
 199 static int zx_pwm_probe(struct platform_device *pdev)
 200 {
 201         struct zx_pwm_chip *zpc;
 202         struct resource *res;
 203         unsigned int i;
 204         int ret;
 205
 206         zpc = devm_kzalloc(&pdev->dev, sizeof(*zpc), GFP_KERNEL);
 207         if (!zpc)
 208                 return -ENOMEM;
 209
 210         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 211         zpc->base = devm_ioremap_resource(&pdev->dev, res);
 212         if (IS_ERR(zpc->base))
 213                 return PTR_ERR(zpc->base);
 214
 215         zpc->pclk = devm_clk_get(&pdev->dev, "pclk");
 216         if (IS_ERR(zpc->pclk))
 217                 return PTR_ERR(zpc->pclk);
 218
 219         zpc->wclk = devm_clk_get(&pdev->dev, "wclk");
 220         if (IS_ERR(zpc->wclk))
 221                 return PTR_ERR(zpc->wclk);
 222
 223         ret = clk_prepare_enable(zpc->pclk);
 224         if (ret)
 225                 return ret;
 226
 227         zpc->chip.dev = &pdev->dev;
 228         zpc->chip.ops = &zx_pwm_ops;
 229         zpc->chip.base = -1;
 230         zpc->chip.npwm = 4;
 231         zpc->chip.of_xlate = of_pwm_xlate_with_flags;
 232         zpc->chip.of_pwm_n_cells = 3;
 233
 234         /*
 235          * PWM devices may be enabled by firmware, and let's disable all of
 236          * them initially to save power.
 237          */
 238         for (i = 0; i < zpc->chip.npwm; i++)
 239                 zx_pwm_set_mask(zpc, i, ZX_PWM_MODE, ZX_PWM_EN, 0);
 240
 241         ret = pwmchip_add(&zpc->chip);
 242         if (ret < 0) {
 243                 dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret);
 244                 return ret;
 245         }
 246
 247         platform_set_drvdata(pdev, zpc);
 248
 249         return 0;
 250 }
 251
 252 static int zx_pwm_remove(struct platform_device *pdev)
 253 {
 254         struct zx_pwm_chip *zpc = platform_get_drvdata(pdev);
 255         int ret;
 256
 257         ret = pwmchip_remove(&zpc->chip);
 258         clk_disable_unprepare(zpc->pclk);
 259
 260         return ret;
 261 }
 262
 263 static const struct of_device_id zx_pwm_dt_ids[] = {
 264         { .compatible = "zte,zx296718-pwm", },
 265         { /* sentinel */ }
 266 };
 267 MODULE_DEVICE_TABLE(of, zx_pwm_dt_ids);
 268
 269 static struct platform_driver zx_pwm_driver = {
 270         .driver = {
 271                 .name = "zx-pwm",
 272                 .of_match_table = zx_pwm_dt_ids,
 273         },
 274         .probe = zx_pwm_probe,
 275         .remove = zx_pwm_remove,
 276 };
 277 module_platform_driver(zx_pwm_driver);
 278
 279 MODULE_ALIAS("platform:zx-pwm");
 280 MODULE_AUTHOR("Shawn Guo <shawn.guo@linaro.org>");
 281 MODULE_DESCRIPTION("ZTE ZX PWM Driver");
 282 MODULE_LICENSE("GPL v2");