drivers/pwm/pwm-vt8500.c

   1 /*
   2  * drivers/pwm/pwm-vt8500.c
   3  *
   4  * Copyright (C) 2012 Tony Prisk <linux@prisktech.co.nz>
   5  * Copyright (C) 2010 Alexey Charkov <alchark@gmail.com>
   6  *
   7  * This software is licensed under the terms of the GNU General Public
   8  * License version 2, as published by the Free Software Foundation, and
   9  * may be copied, distributed, and modified under those terms.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  */
  16
  17 #include <linux/module.h>
  18 #include <linux/kernel.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/slab.h>
  21 #include <linux/err.h>
  22 #include <linux/io.h>
  23 #include <linux/pwm.h>
  24 #include <linux/delay.h>
  25 #include <linux/clk.h>
  26
  27 #include <asm/div64.h>
  28
  29 #include <linux/of.h>
  30 #include <linux/of_device.h>
  31 #include <linux/of_address.h>
  32
  33 /*
  34  * SoC architecture allocates register space for 4 PWMs but only
  35  * 2 are currently implemented.
  36  */
  37 #define VT8500_NR_PWMS  2
  38
  39 #define REG_CTRL(pwm)           (((pwm) << 4) + 0x00)
  40 #define REG_SCALAR(pwm)         (((pwm) << 4) + 0x04)
  41 #define REG_PERIOD(pwm)         (((pwm) << 4) + 0x08)
  42 #define REG_DUTY(pwm)           (((pwm) << 4) + 0x0C)
  43 #define REG_STATUS              0x40
  44
  45 #define CTRL_ENABLE             BIT(0)
  46 #define CTRL_INVERT             BIT(1)
  47 #define CTRL_AUTOLOAD           BIT(2)
  48 #define CTRL_STOP_IMM           BIT(3)
  49 #define CTRL_LOAD_PRESCALE      BIT(4)
  50 #define CTRL_LOAD_PERIOD        BIT(5)
  51
  52 #define STATUS_CTRL_UPDATE      BIT(0)
  53 #define STATUS_SCALAR_UPDATE    BIT(1)
  54 #define STATUS_PERIOD_UPDATE    BIT(2)
  55 #define STATUS_DUTY_UPDATE      BIT(3)
  56 #define STATUS_ALL_UPDATE       0x0F
  57
  58 struct vt8500_chip {
  59         struct pwm_chip chip;
  60         void __iomem *base;
  61         struct clk *clk;
  62 };
  63
  64 #define to_vt8500_chip(chip)    container_of(chip, struct vt8500_chip, chip)
  65
  66 #define msecs_to_loops(t) (loops_per_jiffy / 1000 * HZ * t)
  67 static inline void pwm_busy_wait(struct vt8500_chip *vt8500, int nr, u8 bitmask)
  68 {
  69         int loops = msecs_to_loops(10);
  70         u32 mask = bitmask << (nr << 8);
  71
  72         while ((readl(vt8500->base + REG_STATUS) & mask) && --loops)
  73                 cpu_relax();
  74
  75         if (unlikely(!loops))
  76                 dev_warn(vt8500->chip.dev, "Waiting for status bits 0x%x to clear timed out\n",
  77                          mask);
  78 }
  79
  80 static int vt8500_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
  81                 int duty_ns, int period_ns)
  82 {
  83         struct vt8500_chip *vt8500 = to_vt8500_chip(chip);
  84         unsigned long long c;
  85         unsigned long period_cycles, prescale, pv, dc;
  86         int err;
  87         u32 val;
  88
  89         err = clk_enable(vt8500->clk);
  90         if (err < 0) {
  91                 dev_err(chip->dev, "failed to enable clock\n");
  92                 return err;
  93         }
  94
  95         c = clk_get_rate(vt8500->clk);
  96         c = c * period_ns;
  97         do_div(c, 1000000000);
  98         period_cycles = c;
  99
 100         if (period_cycles < 1)
 101                 period_cycles = 1;
 102         prescale = (period_cycles - 1) / 4096;
 103         pv = period_cycles / (prescale + 1) - 1;
 104         if (pv > 4095)
 105                 pv = 4095;
 106
 107         if (prescale > 1023) {
 108                 clk_disable(vt8500->clk);
 109                 return -EINVAL;
 110         }
 111
 112         c = (unsigned long long)pv * duty_ns;
 113         do_div(c, period_ns);
 114         dc = c;
 115
 116         writel(prescale, vt8500->base + REG_SCALAR(pwm->hwpwm));
 117         pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_SCALAR_UPDATE);
 118
 119         writel(pv, vt8500->base + REG_PERIOD(pwm->hwpwm));
 120         pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_PERIOD_UPDATE);
 121
 122         writel(dc, vt8500->base + REG_DUTY(pwm->hwpwm));
 123         pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_DUTY_UPDATE);
 124
 125         val = readl(vt8500->base + REG_CTRL(pwm->hwpwm));
 126         val |= CTRL_AUTOLOAD;
 127         writel(val, vt8500->base + REG_CTRL(pwm->hwpwm));
 128         pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_CTRL_UPDATE);
 129
 130         clk_disable(vt8500->clk);
 131         return 0;
 132 }
 133
 134 static int vt8500_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 135 {
 136         struct vt8500_chip *vt8500 = to_vt8500_chip(chip);
 137         int err;
 138         u32 val;
 139
 140         err = clk_enable(vt8500->clk);
 141         if (err < 0) {
 142                 dev_err(chip->dev, "failed to enable clock\n");
 143                 return err;
 144         }
 145
 146         val = readl(vt8500->base + REG_CTRL(pwm->hwpwm));
 147         val |= CTRL_ENABLE;
 148         writel(val, vt8500->base + REG_CTRL(pwm->hwpwm));
 149         pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_CTRL_UPDATE);
 150
 151         return 0;
 152 }
 153
 154 static void vt8500_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 155 {
 156         struct vt8500_chip *vt8500 = to_vt8500_chip(chip);
 157         u32 val;
 158
 159         val = readl(vt8500->base + REG_CTRL(pwm->hwpwm));
 160         val &= ~CTRL_ENABLE;
 161         writel(val, vt8500->base + REG_CTRL(pwm->hwpwm));
 162         pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_CTRL_UPDATE);
 163
 164         clk_disable(vt8500->clk);
 165 }
 166
 167 static int vt8500_pwm_set_polarity(struct pwm_chip *chip,
 168                                    struct pwm_device *pwm,
 169                                    enum pwm_polarity polarity)
 170 {
 171         struct vt8500_chip *vt8500 = to_vt8500_chip(chip);
 172         u32 val;
 173
 174         val = readl(vt8500->base + REG_CTRL(pwm->hwpwm));
 175
 176         if (polarity == PWM_POLARITY_INVERSED)
 177                 val |= CTRL_INVERT;
 178         else
 179                 val &= ~CTRL_INVERT;
 180
 181         writel(val, vt8500->base + REG_CTRL(pwm->hwpwm));
 182         pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_CTRL_UPDATE);
 183
 184         return 0;
 185 }
 186
 187 static const struct pwm_ops vt8500_pwm_ops = {
 188         .enable = vt8500_pwm_enable,
 189         .disable = vt8500_pwm_disable,
 190         .config = vt8500_pwm_config,
 191         .set_polarity = vt8500_pwm_set_polarity,
 192         .owner = THIS_MODULE,
 193 };
 194
 195 static const struct of_device_id vt8500_pwm_dt_ids[] = {
 196         { .compatible = "via,vt8500-pwm", },
 197         { /* Sentinel */ }
 198 };
 199 MODULE_DEVICE_TABLE(of, vt8500_pwm_dt_ids);
 200
 201 static int vt8500_pwm_probe(struct platform_device *pdev)
 202 {
 203         struct vt8500_chip *chip;
 204         struct resource *r;
 205         struct device_node *np = pdev->dev.of_node;
 206         int ret;
 207
 208         if (!np) {
 209                 dev_err(&pdev->dev, "invalid devicetree node\n");
 210                 return -EINVAL;
 211         }
 212
 213         chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
 214         if (chip == NULL)
 215                 return -ENOMEM;
 216
 217         chip->chip.dev = &pdev->dev;
 218         chip->chip.ops = &vt8500_pwm_ops;
 219         chip->chip.of_xlate = of_pwm_xlate_with_flags;
 220         chip->chip.of_pwm_n_cells = 3;
 221         chip->chip.base = -1;
 222         chip->chip.npwm = VT8500_NR_PWMS;
 223
 224         chip->clk = devm_clk_get(&pdev->dev, NULL);
 225         if (IS_ERR(chip->clk)) {
 226                 dev_err(&pdev->dev, "clock source not specified\n");
 227                 return PTR_ERR(chip->clk);
 228         }
 229
 230         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 231         chip->base = devm_ioremap_resource(&pdev->dev, r);
 232         if (IS_ERR(chip->base))
 233                 return PTR_ERR(chip->base);
 234
 235         ret = clk_prepare(chip->clk);
 236         if (ret < 0) {
 237                 dev_err(&pdev->dev, "failed to prepare clock\n");
 238                 return ret;
 239         }
 240
 241         ret = pwmchip_add(&chip->chip);
 242         if (ret < 0) {
 243                 dev_err(&pdev->dev, "failed to add PWM chip\n");
 244                 return ret;
 245         }
 246
 247         platform_set_drvdata(pdev, chip);
 248         return ret;
 249 }
 250
 251 static int vt8500_pwm_remove(struct platform_device *pdev)
 252 {
 253         struct vt8500_chip *chip;
 254
 255         chip = platform_get_drvdata(pdev);
 256         if (chip == NULL)
 257                 return -ENODEV;
 258
 259         clk_unprepare(chip->clk);
 260
 261         return pwmchip_remove(&chip->chip);
 262 }
 263
 264 static struct platform_driver vt8500_pwm_driver = {
 265         .probe          = vt8500_pwm_probe,
 266         .remove         = vt8500_pwm_remove,
 267         .driver         = {
 268                 .name   = "vt8500-pwm",
 269                 .of_match_table = vt8500_pwm_dt_ids,
 270         },
 271 };
 272 module_platform_driver(vt8500_pwm_driver);
 273
 274 MODULE_DESCRIPTION("VT8500 PWM Driver");
 275 MODULE_AUTHOR("Tony Prisk <linux@prisktech.co.nz>");
 276 MODULE_LICENSE("GPL v2");