drivers/pwm/pwm-tegra.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * drivers/pwm/pwm-tegra.c
   4  *
   5  * Tegra pulse-width-modulation controller driver
   6  *
   7  * Copyright (c) 2010, NVIDIA Corporation.
   8  * Based on arch/arm/plat-mxc/pwm.c by Sascha Hauer <s.hauer@pengutronix.de>
   9  */
  10
  11 #include <linux/clk.h>
  12 #include <linux/err.h>
  13 #include <linux/io.h>
  14 #include <linux/module.h>
  15 #include <linux/of.h>
  16 #include <linux/of_device.h>
  17 #include <linux/pwm.h>
  18 #include <linux/platform_device.h>
  19 #include <linux/pinctrl/consumer.h>
  20 #include <linux/slab.h>
  21 #include <linux/reset.h>
  22
  23 #define PWM_ENABLE      (1 << 31)
  24 #define PWM_DUTY_WIDTH  8
  25 #define PWM_DUTY_SHIFT  16
  26 #define PWM_SCALE_WIDTH 13
  27 #define PWM_SCALE_SHIFT 0
  28
  29 struct tegra_pwm_soc {
  30         unsigned int num_channels;
  31
  32         /* Maximum IP frequency for given SoCs */
  33         unsigned long max_frequency;
  34 };
  35
  36 struct tegra_pwm_chip {
  37         struct pwm_chip chip;
  38         struct device *dev;
  39
  40         struct clk *clk;
  41         struct reset_control*rst;
  42
  43         unsigned long clk_rate;
  44
  45         void __iomem *regs;
  46
  47         const struct tegra_pwm_soc *soc;
  48 };
  49
  50 static inline struct tegra_pwm_chip *to_tegra_pwm_chip(struct pwm_chip *chip)
  51 {
  52         return container_of(chip, struct tegra_pwm_chip, chip);
  53 }
  54
  55 static inline u32 pwm_readl(struct tegra_pwm_chip *chip, unsigned int num)
  56 {
  57         return readl(chip->regs + (num << 4));
  58 }
  59
  60 static inline void pwm_writel(struct tegra_pwm_chip *chip, unsigned int num,
  61                              unsigned long val)
  62 {
  63         writel(val, chip->regs + (num << 4));
  64 }
  65
  66 static int tegra_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
  67                             int duty_ns, int period_ns)
  68 {
  69         struct tegra_pwm_chip *pc = to_tegra_pwm_chip(chip);
  70         unsigned long long c = duty_ns, hz;
  71         unsigned long rate;
  72         u32 val = 0;
  73         int err;
  74
  75         /*
  76          * Convert from duty_ns / period_ns to a fixed number of duty ticks
  77          * per (1 << PWM_DUTY_WIDTH) cycles and make sure to round to the
  78          * nearest integer during division.
  79          */
  80         c *= (1 << PWM_DUTY_WIDTH);
  81         c = DIV_ROUND_CLOSEST_ULL(c, period_ns);
  82
  83         val = (u32)c << PWM_DUTY_SHIFT;
  84
  85         /*
  86          * Compute the prescaler value for which (1 << PWM_DUTY_WIDTH)
  87          * cycles at the PWM clock rate will take period_ns nanoseconds.
  88          */
  89         rate = pc->clk_rate >> PWM_DUTY_WIDTH;
  90
  91         /* Consider precision in PWM_SCALE_WIDTH rate calculation */
  92         hz = DIV_ROUND_CLOSEST_ULL(100ULL * NSEC_PER_SEC, period_ns);
  93         rate = DIV_ROUND_CLOSEST_ULL(100ULL * rate, hz);
  94
  95         /*
  96          * Since the actual PWM divider is the register's frequency divider
  97          * field minus 1, we need to decrement to get the correct value to
  98          * write to the register.
  99          */
 100         if (rate > 0)
 101                 rate--;
 102
 103         /*
 104          * Make sure that the rate will fit in the register's frequency
 105          * divider field.
 106          */
 107         if (rate >> PWM_SCALE_WIDTH)
 108                 return -EINVAL;
 109
 110         val |= rate << PWM_SCALE_SHIFT;
 111
 112         /*
 113          * If the PWM channel is disabled, make sure to turn on the clock
 114          * before writing the register. Otherwise, keep it enabled.
 115          */
 116         if (!pwm_is_enabled(pwm)) {
 117                 err = clk_prepare_enable(pc->clk);
 118                 if (err < 0)
 119                         return err;
 120         } else
 121                 val |= PWM_ENABLE;
 122
 123         pwm_writel(pc, pwm->hwpwm, val);
 124
 125         /*
 126          * If the PWM is not enabled, turn the clock off again to save power.
 127          */
 128         if (!pwm_is_enabled(pwm))
 129                 clk_disable_unprepare(pc->clk);
 130
 131         return 0;
 132 }
 133
 134 static int tegra_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 135 {
 136         struct tegra_pwm_chip *pc = to_tegra_pwm_chip(chip);
 137         int rc = 0;
 138         u32 val;
 139
 140         rc = clk_prepare_enable(pc->clk);
 141         if (rc < 0)
 142                 return rc;
 143
 144         val = pwm_readl(pc, pwm->hwpwm);
 145         val |= PWM_ENABLE;
 146         pwm_writel(pc, pwm->hwpwm, val);
 147
 148         return 0;
 149 }
 150
 151 static void tegra_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 152 {
 153         struct tegra_pwm_chip *pc = to_tegra_pwm_chip(chip);
 154         u32 val;
 155
 156         val = pwm_readl(pc, pwm->hwpwm);
 157         val &= ~PWM_ENABLE;
 158         pwm_writel(pc, pwm->hwpwm, val);
 159
 160         clk_disable_unprepare(pc->clk);
 161 }
 162
 163 static const struct pwm_ops tegra_pwm_ops = {
 164         .config = tegra_pwm_config,
 165         .enable = tegra_pwm_enable,
 166         .disable = tegra_pwm_disable,
 167         .owner = THIS_MODULE,
 168 };
 169
 170 static int tegra_pwm_probe(struct platform_device *pdev)
 171 {
 172         struct tegra_pwm_chip *pwm;
 173         struct resource *r;
 174         int ret;
 175
 176         pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
 177         if (!pwm)
 178                 return -ENOMEM;
 179
 180         pwm->soc = of_device_get_match_data(&pdev->dev);
 181         pwm->dev = &pdev->dev;
 182
 183         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 184         pwm->regs = devm_ioremap_resource(&pdev->dev, r);
 185         if (IS_ERR(pwm->regs))
 186                 return PTR_ERR(pwm->regs);
 187
 188         platform_set_drvdata(pdev, pwm);
 189
 190         pwm->clk = devm_clk_get(&pdev->dev, NULL);
 191         if (IS_ERR(pwm->clk))
 192                 return PTR_ERR(pwm->clk);
 193
 194         /* Set maximum frequency of the IP */
 195         ret = clk_set_rate(pwm->clk, pwm->soc->max_frequency);
 196         if (ret < 0) {
 197                 dev_err(&pdev->dev, "Failed to set max frequency: %d\n", ret);
 198                 return ret;
 199         }
 200
 201         /*
 202          * The requested and configured frequency may differ due to
 203          * clock register resolutions. Get the configured frequency
 204          * so that PWM period can be calculated more accurately.
 205          */
 206         pwm->clk_rate = clk_get_rate(pwm->clk);
 207
 208         pwm->rst = devm_reset_control_get_exclusive(&pdev->dev, "pwm");
 209         if (IS_ERR(pwm->rst)) {
 210                 ret = PTR_ERR(pwm->rst);
 211                 dev_err(&pdev->dev, "Reset control is not found: %d\n", ret);
 212                 return ret;
 213         }
 214
 215         reset_control_deassert(pwm->rst);
 216
 217         pwm->chip.dev = &pdev->dev;
 218         pwm->chip.ops = &tegra_pwm_ops;
 219         pwm->chip.base = -1;
 220         pwm->chip.npwm = pwm->soc->num_channels;
 221
 222         ret = pwmchip_add(&pwm->chip);
 223         if (ret < 0) {
 224                 dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
 225                 reset_control_assert(pwm->rst);
 226                 return ret;
 227         }
 228
 229         return 0;
 230 }
 231
 232 static int tegra_pwm_remove(struct platform_device *pdev)
 233 {
 234         struct tegra_pwm_chip *pc = platform_get_drvdata(pdev);
 235         unsigned int i;
 236         int err;
 237
 238         if (WARN_ON(!pc))
 239                 return -ENODEV;
 240
 241         err = clk_prepare_enable(pc->clk);
 242         if (err < 0)
 243                 return err;
 244
 245         for (i = 0; i < pc->chip.npwm; i++) {
 246                 struct pwm_device *pwm = &pc->chip.pwms[i];
 247
 248                 if (!pwm_is_enabled(pwm))
 249                         if (clk_prepare_enable(pc->clk) < 0)
 250                                 continue;
 251
 252                 pwm_writel(pc, i, 0);
 253
 254                 clk_disable_unprepare(pc->clk);
 255         }
 256
 257         reset_control_assert(pc->rst);
 258         clk_disable_unprepare(pc->clk);
 259
 260         return pwmchip_remove(&pc->chip);
 261 }
 262
 263 #ifdef CONFIG_PM_SLEEP
 264 static int tegra_pwm_suspend(struct device *dev)
 265 {
 266         return pinctrl_pm_select_sleep_state(dev);
 267 }
 268
 269 static int tegra_pwm_resume(struct device *dev)
 270 {
 271         return pinctrl_pm_select_default_state(dev);
 272 }
 273 #endif
 274
 275 static const struct tegra_pwm_soc tegra20_pwm_soc = {
 276         .num_channels = 4,
 277         .max_frequency = 48000000UL,
 278 };
 279
 280 static const struct tegra_pwm_soc tegra186_pwm_soc = {
 281         .num_channels = 1,
 282         .max_frequency = 102000000UL,
 283 };
 284
 285 static const struct of_device_id tegra_pwm_of_match[] = {
 286         { .compatible = "nvidia,tegra20-pwm", .data = &tegra20_pwm_soc },
 287         { .compatible = "nvidia,tegra186-pwm", .data = &tegra186_pwm_soc },
 288         { }
 289 };
 290 MODULE_DEVICE_TABLE(of, tegra_pwm_of_match);
 291
 292 static const struct dev_pm_ops tegra_pwm_pm_ops = {
 293         SET_SYSTEM_SLEEP_PM_OPS(tegra_pwm_suspend, tegra_pwm_resume)
 294 };
 295
 296 static struct platform_driver tegra_pwm_driver = {
 297         .driver = {
 298                 .name = "tegra-pwm",
 299                 .of_match_table = tegra_pwm_of_match,
 300                 .pm = &tegra_pwm_pm_ops,
 301         },
 302         .probe = tegra_pwm_probe,
 303         .remove = tegra_pwm_remove,
 304 };
 305
 306 module_platform_driver(tegra_pwm_driver);
 307
 308 MODULE_LICENSE("GPL");
 309 MODULE_AUTHOR("NVIDIA Corporation");
 310 MODULE_ALIAS("platform:tegra-pwm");