drivers/pwm/pwm-lpss.c

   1 /*
   2  * Intel Low Power Subsystem PWM controller driver
   3  *
   4  * Copyright (C) 2014, Intel Corporation
   5  * Author: Mika Westerberg <mika.westerberg@linux.intel.com>
   6  * Author: Chew Kean Ho <kean.ho.chew@intel.com>
   7  * Author: Chang Rebecca Swee Fun <rebecca.swee.fun.chang@intel.com>
   8  * Author: Chew Chiau Ee <chiau.ee.chew@intel.com>
   9  * Author: Alan Cox <alan@linux.intel.com>
  10  *
  11  * This program is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License version 2 as
  13  * published by the Free Software Foundation.
  14  */
  15
  16 #include <linux/acpi.h>
  17 #include <linux/clk.h>
  18 #include <linux/device.h>
  19 #include <linux/kernel.h>
  20 #include <linux/module.h>
  21 #include <linux/pwm.h>
  22 #include <linux/platform_device.h>
  23 #include <linux/pci.h>
  24
  25 static int pci_drv, plat_drv;   /* So we know which drivers registered */
  26
  27 #define PWM                             0x00000000
  28 #define PWM_ENABLE                      BIT(31)
  29 #define PWM_SW_UPDATE                   BIT(30)
  30 #define PWM_BASE_UNIT_SHIFT             8
  31 #define PWM_BASE_UNIT_MASK              0x00ffff00
  32 #define PWM_ON_TIME_DIV_MASK            0x000000ff
  33 #define PWM_DIVISION_CORRECTION         0x2
  34 #define PWM_LIMIT                       (0x8000 + PWM_DIVISION_CORRECTION)
  35 #define NSECS_PER_SEC                   1000000000UL
  36
  37 struct pwm_lpss_chip {
  38         struct pwm_chip chip;
  39         void __iomem *regs;
  40         struct clk *clk;
  41         unsigned long clk_rate;
  42 };
  43
  44 struct pwm_lpss_boardinfo {
  45         unsigned long clk_rate;
  46 };
  47
  48 /* BayTrail */
  49 static const struct pwm_lpss_boardinfo byt_info = {
  50         25000000
  51 };
  52
  53 static inline struct pwm_lpss_chip *to_lpwm(struct pwm_chip *chip)
  54 {
  55         return container_of(chip, struct pwm_lpss_chip, chip);
  56 }
  57
  58 static int pwm_lpss_config(struct pwm_chip *chip, struct pwm_device *pwm,
  59                            int duty_ns, int period_ns)
  60 {
  61         struct pwm_lpss_chip *lpwm = to_lpwm(chip);
  62         u8 on_time_div;
  63         unsigned long c;
  64         unsigned long long base_unit, freq = NSECS_PER_SEC;
  65         u32 ctrl;
  66
  67         do_div(freq, period_ns);
  68
  69         /* The equation is: base_unit = ((freq / c) * 65536) + correction */
  70         base_unit = freq * 65536;
  71
  72         c = lpwm->clk_rate;
  73         if (!c)
  74                 return -EINVAL;
  75
  76         do_div(base_unit, c);
  77         base_unit += PWM_DIVISION_CORRECTION;
  78         if (base_unit > PWM_LIMIT)
  79                 return -EINVAL;
  80
  81         if (duty_ns <= 0)
  82                 duty_ns = 1;
  83         on_time_div = 255 - (255 * duty_ns / period_ns);
  84
  85         ctrl = readl(lpwm->regs + PWM);
  86         ctrl &= ~(PWM_BASE_UNIT_MASK | PWM_ON_TIME_DIV_MASK);
  87         ctrl |= (u16) base_unit << PWM_BASE_UNIT_SHIFT;
  88         ctrl |= on_time_div;
  89         /* request PWM to update on next cycle */
  90         ctrl |= PWM_SW_UPDATE;
  91         writel(ctrl, lpwm->regs + PWM);
  92
  93         return 0;
  94 }
  95
  96 static int pwm_lpss_enable(struct pwm_chip *chip, struct pwm_device *pwm)
  97 {
  98         struct pwm_lpss_chip *lpwm = to_lpwm(chip);
  99         u32 ctrl;
 100         int ret;
 101
 102         ret = clk_prepare_enable(lpwm->clk);
 103         if (ret)
 104                 return ret;
 105
 106         ctrl = readl(lpwm->regs + PWM);
 107         writel(ctrl | PWM_ENABLE, lpwm->regs + PWM);
 108
 109         return 0;
 110 }
 111
 112 static void pwm_lpss_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 113 {
 114         struct pwm_lpss_chip *lpwm = to_lpwm(chip);
 115         u32 ctrl;
 116
 117         ctrl = readl(lpwm->regs + PWM);
 118         writel(ctrl & ~PWM_ENABLE, lpwm->regs + PWM);
 119
 120         clk_disable_unprepare(lpwm->clk);
 121 }
 122
 123 static const struct pwm_ops pwm_lpss_ops = {
 124         .config = pwm_lpss_config,
 125         .enable = pwm_lpss_enable,
 126         .disable = pwm_lpss_disable,
 127         .owner = THIS_MODULE,
 128 };
 129
 130 static struct pwm_lpss_chip *pwm_lpss_probe(struct device *dev,
 131                                             struct resource *r,
 132                                             const struct pwm_lpss_boardinfo *info)
 133 {
 134         struct pwm_lpss_chip *lpwm;
 135         int ret;
 136
 137         lpwm = devm_kzalloc(dev, sizeof(*lpwm), GFP_KERNEL);
 138         if (!lpwm)
 139                 return ERR_PTR(-ENOMEM);
 140
 141         lpwm->regs = devm_ioremap_resource(dev, r);
 142         if (IS_ERR(lpwm->regs))
 143                 return ERR_CAST(lpwm->regs);
 144
 145         if (info) {
 146                 lpwm->clk_rate = info->clk_rate;
 147         } else {
 148                 lpwm->clk = devm_clk_get(dev, NULL);
 149                 if (IS_ERR(lpwm->clk)) {
 150                         dev_err(dev, "failed to get PWM clock\n");
 151                         return ERR_CAST(lpwm->clk);
 152                 }
 153                 lpwm->clk_rate = clk_get_rate(lpwm->clk);
 154         }
 155
 156         lpwm->chip.dev = dev;
 157         lpwm->chip.ops = &pwm_lpss_ops;
 158         lpwm->chip.base = -1;
 159         lpwm->chip.npwm = 1;
 160
 161         ret = pwmchip_add(&lpwm->chip);
 162         if (ret) {
 163                 dev_err(dev, "failed to add PWM chip: %d\n", ret);
 164                 return ERR_PTR(ret);
 165         }
 166
 167         return lpwm;
 168 }
 169
 170 static int pwm_lpss_remove(struct pwm_lpss_chip *lpwm)
 171 {
 172         u32 ctrl;
 173
 174         ctrl = readl(lpwm->regs + PWM);
 175         writel(ctrl & ~PWM_ENABLE, lpwm->regs + PWM);
 176
 177         return pwmchip_remove(&lpwm->chip);
 178 }
 179
 180 static int pwm_lpss_probe_pci(struct pci_dev *pdev,
 181                               const struct pci_device_id *id)
 182 {
 183         const struct pwm_lpss_boardinfo *info;
 184         struct pwm_lpss_chip *lpwm;
 185         int err;
 186
 187         err = pci_enable_device(pdev);
 188         if (err < 0)
 189                 return err;
 190
 191         info = (struct pwm_lpss_boardinfo *)id->driver_data;
 192         lpwm = pwm_lpss_probe(&pdev->dev, &pdev->resource[0], info);
 193         if (IS_ERR(lpwm))
 194                 return PTR_ERR(lpwm);
 195
 196         pci_set_drvdata(pdev, lpwm);
 197         return 0;
 198 }
 199
 200 static void pwm_lpss_remove_pci(struct pci_dev *pdev)
 201 {
 202         struct pwm_lpss_chip *lpwm = pci_get_drvdata(pdev);
 203
 204         pwm_lpss_remove(lpwm);
 205         pci_disable_device(pdev);
 206 }
 207
 208 static struct pci_device_id pwm_lpss_pci_ids[] = {
 209         { PCI_VDEVICE(INTEL, 0x0f08), (unsigned long)&byt_info},
 210         { PCI_VDEVICE(INTEL, 0x0f09), (unsigned long)&byt_info},
 211         { },
 212 };
 213 MODULE_DEVICE_TABLE(pci, pwm_lpss_pci_ids);
 214
 215 static struct pci_driver pwm_lpss_driver_pci = {
 216         .name = "pwm-lpss",
 217         .id_table = pwm_lpss_pci_ids,
 218         .probe = pwm_lpss_probe_pci,
 219         .remove = pwm_lpss_remove_pci,
 220 };
 221
 222 static int pwm_lpss_probe_platform(struct platform_device *pdev)
 223 {
 224         struct pwm_lpss_chip *lpwm;
 225         struct resource *r;
 226
 227         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 228
 229         lpwm = pwm_lpss_probe(&pdev->dev, r, NULL);
 230         if (IS_ERR(lpwm))
 231                 return PTR_ERR(lpwm);
 232
 233         platform_set_drvdata(pdev, lpwm);
 234         return 0;
 235 }
 236
 237 static int pwm_lpss_remove_platform(struct platform_device *pdev)
 238 {
 239         struct pwm_lpss_chip *lpwm = platform_get_drvdata(pdev);
 240
 241         return pwm_lpss_remove(lpwm);
 242 }
 243
 244 static const struct acpi_device_id pwm_lpss_acpi_match[] = {
 245         { "80860F09", 0 },
 246         { },
 247 };
 248 MODULE_DEVICE_TABLE(acpi, pwm_lpss_acpi_match);
 249
 250 static struct platform_driver pwm_lpss_driver_platform = {
 251         .driver = {
 252                 .name = "pwm-lpss",
 253                 .acpi_match_table = pwm_lpss_acpi_match,
 254         },
 255         .probe = pwm_lpss_probe_platform,
 256         .remove = pwm_lpss_remove_platform,
 257 };
 258
 259 static int __init pwm_init(void)
 260 {
 261         pci_drv = pci_register_driver(&pwm_lpss_driver_pci);
 262         plat_drv = platform_driver_register(&pwm_lpss_driver_platform);
 263         if (pci_drv && plat_drv)
 264                 return pci_drv;
 265
 266         return 0;
 267 }
 268 module_init(pwm_init);
 269
 270 static void __exit pwm_exit(void)
 271 {
 272         if (!pci_drv)
 273                 pci_unregister_driver(&pwm_lpss_driver_pci);
 274         if (!plat_drv)
 275                 platform_driver_unregister(&pwm_lpss_driver_platform);
 276 }
 277 module_exit(pwm_exit);
 278
 279 MODULE_DESCRIPTION("PWM driver for Intel LPSS");
 280 MODULE_AUTHOR("Mika Westerberg <mika.westerberg@linux.intel.com>");
 281 MODULE_LICENSE("GPL v2");
 282 MODULE_ALIAS("platform:pwm-lpss");