kernel/drivers/pwm/pwm-img.c

   1 /*
   2  * Imagination Technologies Pulse Width Modulator driver
   3  *
   4  * Copyright (c) 2014-2015, Imagination Technologies
   5  *
   6  * Based on drivers/pwm/pwm-tegra.c, Copyright (c) 2010, NVIDIA Corporation
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License.
  11  */
  12
  13 #include <linux/clk.h>
  14 #include <linux/err.h>
  15 #include <linux/io.h>
  16 #include <linux/mfd/syscon.h>
  17 #include <linux/module.h>
  18 #include <linux/of.h>
  19 #include <linux/of_device.h>
  20 #include <linux/platform_device.h>
  21 #include <linux/pwm.h>
  22 #include <linux/regmap.h>
  23 #include <linux/slab.h>
  24
  25 /* PWM registers */
  26 #define PWM_CTRL_CFG                            0x0000
  27 #define PWM_CTRL_CFG_NO_SUB_DIV                 0
  28 #define PWM_CTRL_CFG_SUB_DIV0                   1
  29 #define PWM_CTRL_CFG_SUB_DIV1                   2
  30 #define PWM_CTRL_CFG_SUB_DIV0_DIV1              3
  31 #define PWM_CTRL_CFG_DIV_SHIFT(ch)              ((ch) * 2 + 4)
  32 #define PWM_CTRL_CFG_DIV_MASK                   0x3
  33
  34 #define PWM_CH_CFG(ch)                          (0x4 + (ch) * 4)
  35 #define PWM_CH_CFG_TMBASE_SHIFT                 0
  36 #define PWM_CH_CFG_DUTY_SHIFT                   16
  37
  38 #define PERIP_PWM_PDM_CONTROL                   0x0140
  39 #define PERIP_PWM_PDM_CONTROL_CH_MASK           0x1
  40 #define PERIP_PWM_PDM_CONTROL_CH_SHIFT(ch)      ((ch) * 4)
  41
  42 /*
  43  * PWM period is specified with a timebase register,
  44  * in number of step periods. The PWM duty cycle is also
  45  * specified in step periods, in the [0, $timebase] range.
  46  * In other words, the timebase imposes the duty cycle
  47  * resolution. Therefore, let's constraint the timebase to
  48  * a minimum value to allow a sane range of duty cycle values.
  49  * Imposing a minimum timebase, will impose a maximum PWM frequency.
  50  *
  51  * The value chosen is completely arbitrary.
  52  */
  53 #define MIN_TMBASE_STEPS                        16
  54
  55 struct img_pwm_soc_data {
  56         u32 max_timebase;
  57 };
  58
  59 struct img_pwm_chip {
  60         struct device   *dev;
  61         struct pwm_chip chip;
  62         struct clk      *pwm_clk;
  63         struct clk      *sys_clk;
  64         void __iomem    *base;
  65         struct regmap   *periph_regs;
  66         int             max_period_ns;
  67         int             min_period_ns;
  68         const struct img_pwm_soc_data   *data;
  69 };
  70
  71 static inline struct img_pwm_chip *to_img_pwm_chip(struct pwm_chip *chip)
  72 {
  73         return container_of(chip, struct img_pwm_chip, chip);
  74 }
  75
  76 static inline void img_pwm_writel(struct img_pwm_chip *chip,
  77                                   u32 reg, u32 val)
  78 {
  79         writel(val, chip->base + reg);
  80 }
  81
  82 static inline u32 img_pwm_readl(struct img_pwm_chip *chip,
  83                                          u32 reg)
  84 {
  85         return readl(chip->base + reg);
  86 }
  87
  88 static int img_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
  89                           int duty_ns, int period_ns)
  90 {
  91         u32 val, div, duty, timebase;
  92         unsigned long mul, output_clk_hz, input_clk_hz;
  93         struct img_pwm_chip *pwm_chip = to_img_pwm_chip(chip);
  94         unsigned int max_timebase = pwm_chip->data->max_timebase;
  95
  96         if (period_ns < pwm_chip->min_period_ns ||
  97             period_ns > pwm_chip->max_period_ns) {
  98                 dev_err(chip->dev, "configured period not in range\n");
  99                 return -ERANGE;
 100         }
 101
 102         input_clk_hz = clk_get_rate(pwm_chip->pwm_clk);
 103         output_clk_hz = DIV_ROUND_UP(NSEC_PER_SEC, period_ns);
 104
 105         mul = DIV_ROUND_UP(input_clk_hz, output_clk_hz);
 106         if (mul <= max_timebase) {
 107                 div = PWM_CTRL_CFG_NO_SUB_DIV;
 108                 timebase = DIV_ROUND_UP(mul, 1);
 109         } else if (mul <= max_timebase * 8) {
 110                 div = PWM_CTRL_CFG_SUB_DIV0;
 111                 timebase = DIV_ROUND_UP(mul, 8);
 112         } else if (mul <= max_timebase * 64) {
 113                 div = PWM_CTRL_CFG_SUB_DIV1;
 114                 timebase = DIV_ROUND_UP(mul, 64);
 115         } else if (mul <= max_timebase * 512) {
 116                 div = PWM_CTRL_CFG_SUB_DIV0_DIV1;
 117                 timebase = DIV_ROUND_UP(mul, 512);
 118         } else if (mul > max_timebase * 512) {
 119                 dev_err(chip->dev,
 120                         "failed to configure timebase steps/divider value\n");
 121                 return -EINVAL;
 122         }
 123
 124         duty = DIV_ROUND_UP(timebase * duty_ns, period_ns);
 125
 126         val = img_pwm_readl(pwm_chip, PWM_CTRL_CFG);
 127         val &= ~(PWM_CTRL_CFG_DIV_MASK << PWM_CTRL_CFG_DIV_SHIFT(pwm->hwpwm));
 128         val |= (div & PWM_CTRL_CFG_DIV_MASK) <<
 129                 PWM_CTRL_CFG_DIV_SHIFT(pwm->hwpwm);
 130         img_pwm_writel(pwm_chip, PWM_CTRL_CFG, val);
 131
 132         val = (duty << PWM_CH_CFG_DUTY_SHIFT) |
 133               (timebase << PWM_CH_CFG_TMBASE_SHIFT);
 134         img_pwm_writel(pwm_chip, PWM_CH_CFG(pwm->hwpwm), val);
 135
 136         return 0;
 137 }
 138
 139 static int img_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 140 {
 141         u32 val;
 142         struct img_pwm_chip *pwm_chip = to_img_pwm_chip(chip);
 143
 144         val = img_pwm_readl(pwm_chip, PWM_CTRL_CFG);
 145         val |= BIT(pwm->hwpwm);
 146         img_pwm_writel(pwm_chip, PWM_CTRL_CFG, val);
 147
 148         regmap_update_bits(pwm_chip->periph_regs, PERIP_PWM_PDM_CONTROL,
 149                            PERIP_PWM_PDM_CONTROL_CH_MASK <<
 150                            PERIP_PWM_PDM_CONTROL_CH_SHIFT(pwm->hwpwm), 0);
 151
 152         return 0;
 153 }
 154
 155 static void img_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 156 {
 157         u32 val;
 158         struct img_pwm_chip *pwm_chip = to_img_pwm_chip(chip);
 159
 160         val = img_pwm_readl(pwm_chip, PWM_CTRL_CFG);
 161         val &= ~BIT(pwm->hwpwm);
 162         img_pwm_writel(pwm_chip, PWM_CTRL_CFG, val);
 163 }
 164
 165 static const struct pwm_ops img_pwm_ops = {
 166         .config = img_pwm_config,
 167         .enable = img_pwm_enable,
 168         .disable = img_pwm_disable,
 169         .owner = THIS_MODULE,
 170 };
 171
 172 static const struct img_pwm_soc_data pistachio_pwm = {
 173         .max_timebase = 255,
 174 };
 175
 176 static const struct of_device_id img_pwm_of_match[] = {
 177         {
 178                 .compatible = "img,pistachio-pwm",
 179                 .data = &pistachio_pwm,
 180         },
 181         { }
 182 };
 183 MODULE_DEVICE_TABLE(of, img_pwm_of_match);
 184
 185 static int img_pwm_probe(struct platform_device *pdev)
 186 {
 187         int ret;
 188         u64 val;
 189         unsigned long clk_rate;
 190         struct resource *res;
 191         struct img_pwm_chip *pwm;
 192         const struct of_device_id *of_dev_id;
 193
 194         pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
 195         if (!pwm)
 196                 return -ENOMEM;
 197
 198         pwm->dev = &pdev->dev;
 199
 200         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 201         pwm->base = devm_ioremap_resource(&pdev->dev, res);
 202         if (IS_ERR(pwm->base))
 203                 return PTR_ERR(pwm->base);
 204
 205         of_dev_id = of_match_device(img_pwm_of_match, &pdev->dev);
 206         if (!of_dev_id)
 207                 return -ENODEV;
 208         pwm->data = of_dev_id->data;
 209
 210         pwm->periph_regs = syscon_regmap_lookup_by_phandle(pdev->dev.of_node,
 211                                                            "img,cr-periph");
 212         if (IS_ERR(pwm->periph_regs))
 213                 return PTR_ERR(pwm->periph_regs);
 214
 215         pwm->sys_clk = devm_clk_get(&pdev->dev, "sys");
 216         if (IS_ERR(pwm->sys_clk)) {
 217                 dev_err(&pdev->dev, "failed to get system clock\n");
 218                 return PTR_ERR(pwm->sys_clk);
 219         }
 220
 221         pwm->pwm_clk = devm_clk_get(&pdev->dev, "pwm");
 222         if (IS_ERR(pwm->pwm_clk)) {
 223                 dev_err(&pdev->dev, "failed to get pwm clock\n");
 224                 return PTR_ERR(pwm->pwm_clk);
 225         }
 226
 227         ret = clk_prepare_enable(pwm->sys_clk);
 228         if (ret < 0) {
 229                 dev_err(&pdev->dev, "could not prepare or enable sys clock\n");
 230                 return ret;
 231         }
 232
 233         ret = clk_prepare_enable(pwm->pwm_clk);
 234         if (ret < 0) {
 235                 dev_err(&pdev->dev, "could not prepare or enable pwm clock\n");
 236                 goto disable_sysclk;
 237         }
 238
 239         clk_rate = clk_get_rate(pwm->pwm_clk);
 240
 241         /* The maximum input clock divider is 512 */
 242         val = (u64)NSEC_PER_SEC * 512 * pwm->data->max_timebase;
 243         do_div(val, clk_rate);
 244         pwm->max_period_ns = val;
 245
 246         val = (u64)NSEC_PER_SEC * MIN_TMBASE_STEPS;
 247         do_div(val, clk_rate);
 248         pwm->min_period_ns = val;
 249
 250         pwm->chip.dev = &pdev->dev;
 251         pwm->chip.ops = &img_pwm_ops;
 252         pwm->chip.base = -1;
 253         pwm->chip.npwm = 4;
 254
 255         ret = pwmchip_add(&pwm->chip);
 256         if (ret < 0) {
 257                 dev_err(&pdev->dev, "pwmchip_add failed: %d\n", ret);
 258                 goto disable_pwmclk;
 259         }
 260
 261         platform_set_drvdata(pdev, pwm);
 262         return 0;
 263
 264 disable_pwmclk:
 265         clk_disable_unprepare(pwm->pwm_clk);
 266 disable_sysclk:
 267         clk_disable_unprepare(pwm->sys_clk);
 268         return ret;
 269 }
 270
 271 static int img_pwm_remove(struct platform_device *pdev)
 272 {
 273         struct img_pwm_chip *pwm_chip = platform_get_drvdata(pdev);
 274         u32 val;
 275         unsigned int i;
 276
 277         for (i = 0; i < pwm_chip->chip.npwm; i++) {
 278                 val = img_pwm_readl(pwm_chip, PWM_CTRL_CFG);
 279                 val &= ~BIT(i);
 280                 img_pwm_writel(pwm_chip, PWM_CTRL_CFG, val);
 281         }
 282
 283         clk_disable_unprepare(pwm_chip->pwm_clk);
 284         clk_disable_unprepare(pwm_chip->sys_clk);
 285
 286         return pwmchip_remove(&pwm_chip->chip);
 287 }
 288
 289 static struct platform_driver img_pwm_driver = {
 290         .driver = {
 291                 .name = "img-pwm",
 292                 .of_match_table = img_pwm_of_match,
 293         },
 294         .probe = img_pwm_probe,
 295         .remove = img_pwm_remove,
 296 };
 297 module_platform_driver(img_pwm_driver);
 298
 299 MODULE_AUTHOR("Sai Masarapu <Sai.Masarapu@imgtec.com>");
 300 MODULE_DESCRIPTION("Imagination Technologies PWM DAC driver");
 301 MODULE_LICENSE("GPL v2");