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 *
 10 * This program is free software; you can redistribute it and/or modify
 11 * it under the terms of the GNU General Public License version 2 as
 12 * published by the Free Software Foundation.
 13 */
 14
 15#include <linux/acpi.h>
 16#include <linux/clk.h>
 17#include <linux/device.h>
 18#include <linux/kernel.h>
 19#include <linux/module.h>
 20#include <linux/pwm.h>
 21#include <linux/platform_device.h>
 22
 23#define PWM				0x00000000
 24#define PWM_ENABLE			BIT(31)
 25#define PWM_SW_UPDATE			BIT(30)
 26#define PWM_BASE_UNIT_SHIFT		8
 27#define PWM_BASE_UNIT_MASK		0x00ffff00
 28#define PWM_ON_TIME_DIV_MASK		0x000000ff
 29#define PWM_DIVISION_CORRECTION		0x2
 30#define PWM_LIMIT			(0x8000 + PWM_DIVISION_CORRECTION)
 31#define NSECS_PER_SEC			1000000000UL
 32
 33struct pwm_lpss_chip {
 34	struct pwm_chip chip;
 35	void __iomem *regs;
 36	struct clk *clk;
 37};
 38
 39static inline struct pwm_lpss_chip *to_lpwm(struct pwm_chip *chip)
 40{
 41	return container_of(chip, struct pwm_lpss_chip, chip);
 42}
 43
 44static int pwm_lpss_config(struct pwm_chip *chip, struct pwm_device *pwm,
 45			   int duty_ns, int period_ns)
 46{
 47	struct pwm_lpss_chip *lpwm = to_lpwm(chip);
 48	u8 on_time_div;
 49	unsigned long c;
 50	unsigned long long base_unit, freq = NSECS_PER_SEC;
 51	u32 ctrl;
 52
 53	do_div(freq, period_ns);
 54
 55	/* The equation is: base_unit = ((freq / c) * 65536) + correction */
 56	base_unit = freq * 65536;
 57
 58	c = clk_get_rate(lpwm->clk);
 59	if (!c)
 60		return -EINVAL;
 61
 62	do_div(base_unit, c);
 63	base_unit += PWM_DIVISION_CORRECTION;
 64	if (base_unit > PWM_LIMIT)
 65		return -EINVAL;
 66
 67	if (duty_ns <= 0)
 68		duty_ns = 1;
 69	on_time_div = 255 - (255 * duty_ns / period_ns);
 70
 71	ctrl = readl(lpwm->regs + PWM);
 72	ctrl &= ~(PWM_BASE_UNIT_MASK | PWM_ON_TIME_DIV_MASK);
 73	ctrl |= (u16) base_unit << PWM_BASE_UNIT_SHIFT;
 74	ctrl |= on_time_div;
 75	/* request PWM to update on next cycle */
 76	ctrl |= PWM_SW_UPDATE;
 77	writel(ctrl, lpwm->regs + PWM);
 78
 79	return 0;
 80}
 81
 82static int pwm_lpss_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 83{
 84	struct pwm_lpss_chip *lpwm = to_lpwm(chip);
 85	u32 ctrl;
 86	int ret;
 87
 88	ret = clk_prepare_enable(lpwm->clk);
 89	if (ret)
 90		return ret;
 91
 92	ctrl = readl(lpwm->regs + PWM);
 93	writel(ctrl | PWM_ENABLE, lpwm->regs + PWM);
 94
 95	return 0;
 96}
 97
 98static void pwm_lpss_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 99{
100	struct pwm_lpss_chip *lpwm = to_lpwm(chip);
101	u32 ctrl;
102
103	ctrl = readl(lpwm->regs + PWM);
104	writel(ctrl & ~PWM_ENABLE, lpwm->regs + PWM);
105
106	clk_disable_unprepare(lpwm->clk);
107}
108
109static const struct pwm_ops pwm_lpss_ops = {
110	.config = pwm_lpss_config,
111	.enable = pwm_lpss_enable,
112	.disable = pwm_lpss_disable,
113	.owner = THIS_MODULE,
114};
115
116static const struct acpi_device_id pwm_lpss_acpi_match[] = {
117	{ "80860F09", 0 },
118	{ },
119};
120MODULE_DEVICE_TABLE(acpi, pwm_lpss_acpi_match);
121
122static int pwm_lpss_probe(struct platform_device *pdev)
123{
124	struct pwm_lpss_chip *lpwm;
125	struct resource *r;
126	int ret;
127
128	lpwm = devm_kzalloc(&pdev->dev, sizeof(*lpwm), GFP_KERNEL);
129	if (!lpwm)
130		return -ENOMEM;
131
132	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
133
134	lpwm->regs = devm_ioremap_resource(&pdev->dev, r);
135	if (IS_ERR(lpwm->regs))
136		return PTR_ERR(lpwm->regs);
137
138	lpwm->clk = devm_clk_get(&pdev->dev, NULL);
139	if (IS_ERR(lpwm->clk)) {
140		dev_err(&pdev->dev, "failed to get PWM clock\n");
141		return PTR_ERR(lpwm->clk);
142	}
143
144	lpwm->chip.dev = &pdev->dev;
145	lpwm->chip.ops = &pwm_lpss_ops;
146	lpwm->chip.base = -1;
147	lpwm->chip.npwm = 1;
148
149	ret = pwmchip_add(&lpwm->chip);
150	if (ret) {
151		dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret);
152		return ret;
153	}
154
155	platform_set_drvdata(pdev, lpwm);
156	return 0;
157}
158
159static int pwm_lpss_remove(struct platform_device *pdev)
160{
161	struct pwm_lpss_chip *lpwm = platform_get_drvdata(pdev);
162	u32 ctrl;
163
164	ctrl = readl(lpwm->regs + PWM);
165	writel(ctrl & ~PWM_ENABLE, lpwm->regs + PWM);
166
167	return pwmchip_remove(&lpwm->chip);
168}
169
170static struct platform_driver pwm_lpss_driver = {
171	.driver = {
172		.name = "pwm-lpss",
173		.acpi_match_table = pwm_lpss_acpi_match,
174	},
175	.probe = pwm_lpss_probe,
176	.remove = pwm_lpss_remove,
177};
178module_platform_driver(pwm_lpss_driver);
179
180MODULE_DESCRIPTION("PWM driver for Intel LPSS");
181MODULE_AUTHOR("Mika Westerberg <mika.westerberg@linux.intel.com>");
182MODULE_LICENSE("GPL v2");
183MODULE_ALIAS("platform:pwm-lpss");