drivers/pwm/pwm-vt8500.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * drivers/pwm/pwm-vt8500.c
   4  *
   5  * Copyright (C) 2012 Tony Prisk <linux@prisktech.co.nz>
   6  * Copyright (C) 2010 Alexey Charkov <alchark@gmail.com>
   7  */
   8
   9 #include <linux/module.h>
  10 #include <linux/kernel.h>
  11 #include <linux/platform_device.h>
  12 #include <linux/slab.h>
  13 #include <linux/err.h>
  14 #include <linux/io.h>
  15 #include <linux/pwm.h>
  16 #include <linux/delay.h>
  17 #include <linux/clk.h>
  18
  19 #include <asm/div64.h>
  20
  21 #include <linux/of.h>
  22 #include <linux/of_device.h>
  23 #include <linux/of_address.h>
  24
  25 /*
  26  * SoC architecture allocates register space for 4 PWMs but only
  27  * 2 are currently implemented.
  28  */
  29 #define VT8500_NR_PWMS  2
  30
  31 #define REG_CTRL(pwm)           (((pwm) << 4) + 0x00)
  32 #define REG_SCALAR(pwm)         (((pwm) << 4) + 0x04)
  33 #define REG_PERIOD(pwm)         (((pwm) << 4) + 0x08)
  34 #define REG_DUTY(pwm)           (((pwm) << 4) + 0x0C)
  35 #define REG_STATUS              0x40
  36
  37 #define CTRL_ENABLE             BIT(0)
  38 #define CTRL_INVERT             BIT(1)
  39 #define CTRL_AUTOLOAD           BIT(2)
  40 #define CTRL_STOP_IMM           BIT(3)
  41 #define CTRL_LOAD_PRESCALE      BIT(4)
  42 #define CTRL_LOAD_PERIOD        BIT(5)
  43
  44 #define STATUS_CTRL_UPDATE      BIT(0)
  45 #define STATUS_SCALAR_UPDATE    BIT(1)
  46 #define STATUS_PERIOD_UPDATE    BIT(2)
  47 #define STATUS_DUTY_UPDATE      BIT(3)
  48 #define STATUS_ALL_UPDATE       0x0F
  49
  50 struct vt8500_chip {
  51         struct pwm_chip chip;
  52         void __iomem *base;
  53         struct clk *clk;
  54 };
  55
  56 #define to_vt8500_chip(chip)    container_of(chip, struct vt8500_chip, chip)
  57
  58 #define msecs_to_loops(t) (loops_per_jiffy / 1000 * HZ * t)
  59 static inline void pwm_busy_wait(struct vt8500_chip *vt8500, int nr, u8 bitmask)
  60 {
  61         int loops = msecs_to_loops(10);
  62         u32 mask = bitmask << (nr << 8);
  63
  64         while ((readl(vt8500->base + REG_STATUS) & mask) && --loops)
  65                 cpu_relax();
  66
  67         if (unlikely(!loops))
  68                 dev_warn(vt8500->chip.dev, "Waiting for status bits 0x%x to clear timed out\n",
  69                          mask);
  70 }
  71
  72 static int vt8500_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
  73                 int duty_ns, int period_ns)
  74 {
  75         struct vt8500_chip *vt8500 = to_vt8500_chip(chip);
  76         unsigned long long c;
  77         unsigned long period_cycles, prescale, pv, dc;
  78         int err;
  79         u32 val;
  80
  81         err = clk_enable(vt8500->clk);
  82         if (err < 0) {
  83                 dev_err(chip->dev, "failed to enable clock\n");
  84                 return err;
  85         }
  86
  87         c = clk_get_rate(vt8500->clk);
  88         c = c * period_ns;
  89         do_div(c, 1000000000);
  90         period_cycles = c;
  91
  92         if (period_cycles < 1)
  93                 period_cycles = 1;
  94         prescale = (period_cycles - 1) / 4096;
  95         pv = period_cycles / (prescale + 1) - 1;
  96         if (pv > 4095)
  97                 pv = 4095;
  98
  99         if (prescale > 1023) {
 100                 clk_disable(vt8500->clk);
 101                 return -EINVAL;
 102         }
 103
 104         c = (unsigned long long)pv * duty_ns;
 105         do_div(c, period_ns);
 106         dc = c;
 107
 108         writel(prescale, vt8500->base + REG_SCALAR(pwm->hwpwm));
 109         pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_SCALAR_UPDATE);
 110
 111         writel(pv, vt8500->base + REG_PERIOD(pwm->hwpwm));
 112         pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_PERIOD_UPDATE);
 113
 114         writel(dc, vt8500->base + REG_DUTY(pwm->hwpwm));
 115         pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_DUTY_UPDATE);
 116
 117         val = readl(vt8500->base + REG_CTRL(pwm->hwpwm));
 118         val |= CTRL_AUTOLOAD;
 119         writel(val, vt8500->base + REG_CTRL(pwm->hwpwm));
 120         pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_CTRL_UPDATE);
 121
 122         clk_disable(vt8500->clk);
 123         return 0;
 124 }
 125
 126 static int vt8500_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 127 {
 128         struct vt8500_chip *vt8500 = to_vt8500_chip(chip);
 129         int err;
 130         u32 val;
 131
 132         err = clk_enable(vt8500->clk);
 133         if (err < 0) {
 134                 dev_err(chip->dev, "failed to enable clock\n");
 135                 return err;
 136         }
 137
 138         val = readl(vt8500->base + REG_CTRL(pwm->hwpwm));
 139         val |= CTRL_ENABLE;
 140         writel(val, vt8500->base + REG_CTRL(pwm->hwpwm));
 141         pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_CTRL_UPDATE);
 142
 143         return 0;
 144 }
 145
 146 static void vt8500_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 147 {
 148         struct vt8500_chip *vt8500 = to_vt8500_chip(chip);
 149         u32 val;
 150
 151         val = readl(vt8500->base + REG_CTRL(pwm->hwpwm));
 152         val &= ~CTRL_ENABLE;
 153         writel(val, vt8500->base + REG_CTRL(pwm->hwpwm));
 154         pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_CTRL_UPDATE);
 155
 156         clk_disable(vt8500->clk);
 157 }
 158
 159 static int vt8500_pwm_set_polarity(struct pwm_chip *chip,
 160                                    struct pwm_device *pwm,
 161                                    enum pwm_polarity polarity)
 162 {
 163         struct vt8500_chip *vt8500 = to_vt8500_chip(chip);
 164         u32 val;
 165
 166         val = readl(vt8500->base + REG_CTRL(pwm->hwpwm));
 167
 168         if (polarity == PWM_POLARITY_INVERSED)
 169                 val |= CTRL_INVERT;
 170         else
 171                 val &= ~CTRL_INVERT;
 172
 173         writel(val, vt8500->base + REG_CTRL(pwm->hwpwm));
 174         pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_CTRL_UPDATE);
 175
 176         return 0;
 177 }
 178
 179 static const struct pwm_ops vt8500_pwm_ops = {
 180         .enable = vt8500_pwm_enable,
 181         .disable = vt8500_pwm_disable,
 182         .config = vt8500_pwm_config,
 183         .set_polarity = vt8500_pwm_set_polarity,
 184         .owner = THIS_MODULE,
 185 };
 186
 187 static const struct of_device_id vt8500_pwm_dt_ids[] = {
 188         { .compatible = "via,vt8500-pwm", },
 189         { /* Sentinel */ }
 190 };
 191 MODULE_DEVICE_TABLE(of, vt8500_pwm_dt_ids);
 192
 193 static int vt8500_pwm_probe(struct platform_device *pdev)
 194 {
 195         struct vt8500_chip *chip;
 196         struct device_node *np = pdev->dev.of_node;
 197         int ret;
 198
 199         if (!np) {
 200                 dev_err(&pdev->dev, "invalid devicetree node\n");
 201                 return -EINVAL;
 202         }
 203
 204         chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
 205         if (chip == NULL)
 206                 return -ENOMEM;
 207
 208         chip->chip.dev = &pdev->dev;
 209         chip->chip.ops = &vt8500_pwm_ops;
 210         chip->chip.npwm = VT8500_NR_PWMS;
 211
 212         chip->clk = devm_clk_get(&pdev->dev, NULL);
 213         if (IS_ERR(chip->clk)) {
 214                 dev_err(&pdev->dev, "clock source not specified\n");
 215                 return PTR_ERR(chip->clk);
 216         }
 217
 218         chip->base = devm_platform_ioremap_resource(pdev, 0);
 219         if (IS_ERR(chip->base))
 220                 return PTR_ERR(chip->base);
 221
 222         ret = clk_prepare(chip->clk);
 223         if (ret < 0) {
 224                 dev_err(&pdev->dev, "failed to prepare clock\n");
 225                 return ret;
 226         }
 227
 228         ret = pwmchip_add(&chip->chip);
 229         if (ret < 0) {
 230                 dev_err(&pdev->dev, "failed to add PWM chip\n");
 231                 clk_unprepare(chip->clk);
 232                 return ret;
 233         }
 234
 235         platform_set_drvdata(pdev, chip);
 236         return ret;
 237 }
 238
 239 static int vt8500_pwm_remove(struct platform_device *pdev)
 240 {
 241         struct vt8500_chip *chip = platform_get_drvdata(pdev);
 242
 243         pwmchip_remove(&chip->chip);
 244
 245         clk_unprepare(chip->clk);
 246
 247         return 0;
 248 }
 249
 250 static struct platform_driver vt8500_pwm_driver = {
 251         .probe          = vt8500_pwm_probe,
 252         .remove         = vt8500_pwm_remove,
 253         .driver         = {
 254                 .name   = "vt8500-pwm",
 255                 .of_match_table = vt8500_pwm_dt_ids,
 256         },
 257 };
 258 module_platform_driver(vt8500_pwm_driver);
 259
 260 MODULE_DESCRIPTION("VT8500 PWM Driver");
 261 MODULE_AUTHOR("Tony Prisk <linux@prisktech.co.nz>");
 262 MODULE_LICENSE("GPL v2");