1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Intel Keem Bay PWM driver
  4 *
  5 * Copyright (C) 2020 Intel Corporation
  6 * Authors: Lai Poey Seng <poey.seng.lai@intel.com>
  7 *          Vineetha G. Jaya Kumaran <vineetha.g.jaya.kumaran@intel.com>
  8 *
  9 * Limitations:
 10 * - Upon disabling a channel, the currently running
 11 *   period will not be completed. However, upon
 12 *   reconfiguration of the duty cycle/period, the
 13 *   currently running period will be completed first.
 14 */
 15
 16#include <linux/bitfield.h>
 17#include <linux/clk.h>
 18#include <linux/io.h>
 19#include <linux/mod_devicetable.h>
 20#include <linux/module.h>
 21#include <linux/platform_device.h>
 22#include <linux/pwm.h>
 23#include <linux/regmap.h>
 24
 25#define KMB_TOTAL_PWM_CHANNELS		6
 26#define KMB_PWM_COUNT_MAX		U16_MAX
 27#define KMB_PWM_EN_BIT			BIT(31)
 28
 29/* Mask */
 30#define KMB_PWM_HIGH_MASK		GENMASK(31, 16)
 31#define KMB_PWM_LOW_MASK		GENMASK(15, 0)
 32#define KMB_PWM_LEADIN_MASK		GENMASK(30, 0)
 33
 34/* PWM Register offset */
 35#define KMB_PWM_LEADIN_OFFSET(ch)	(0x00 + 4 * (ch))
 36#define KMB_PWM_HIGHLOW_OFFSET(ch)	(0x20 + 4 * (ch))
 37
 38struct keembay_pwm {
 39	struct device *dev;
 40	struct clk *clk;
 41	void __iomem *base;
 42};
 43
 44static inline struct keembay_pwm *to_keembay_pwm_dev(struct pwm_chip *chip)
 45{
 46	return pwmchip_get_drvdata(chip);
 47}
 48
 49static void keembay_clk_unprepare(void *data)
 50{
 51	clk_disable_unprepare(data);
 52}
 53
 54static int keembay_clk_enable(struct device *dev, struct clk *clk)
 55{
 56	int ret;
 57
 58	ret = clk_prepare_enable(clk);
 59	if (ret)
 60		return ret;
 61
 62	return devm_add_action_or_reset(dev, keembay_clk_unprepare, clk);
 63}
 64
 65/*
 66 * With gcc 10, CONFIG_CC_OPTIMIZE_FOR_SIZE and only "inline" instead of
 67 * "__always_inline" this fails to compile because the compiler doesn't notice
 68 * for all valid masks (e.g. KMB_PWM_LEADIN_MASK) that they are ok.
 69 */
 70static __always_inline void keembay_pwm_update_bits(struct keembay_pwm *priv, u32 mask,
 71					   u32 val, u32 offset)
 72{
 73	u32 buff = readl(priv->base + offset);
 74
 75	buff = u32_replace_bits(buff, val, mask);
 76	writel(buff, priv->base + offset);
 77}
 78
 79static void keembay_pwm_enable(struct keembay_pwm *priv, int ch)
 80{
 81	keembay_pwm_update_bits(priv, KMB_PWM_EN_BIT, 1,
 82				KMB_PWM_LEADIN_OFFSET(ch));
 83}
 84
 85static void keembay_pwm_disable(struct keembay_pwm *priv, int ch)
 86{
 87	keembay_pwm_update_bits(priv, KMB_PWM_EN_BIT, 0,
 88				KMB_PWM_LEADIN_OFFSET(ch));
 89}
 90
 91static int keembay_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 92				 struct pwm_state *state)
 93{
 94	struct keembay_pwm *priv = to_keembay_pwm_dev(chip);
 95	unsigned long long high, low;
 96	unsigned long clk_rate;
 97	u32 highlow;
 98
 99	clk_rate = clk_get_rate(priv->clk);
100
101	/* Read channel enabled status */
102	highlow = readl(priv->base + KMB_PWM_LEADIN_OFFSET(pwm->hwpwm));
103	if (highlow & KMB_PWM_EN_BIT)
104		state->enabled = true;
105	else
106		state->enabled = false;
107
108	/* Read period and duty cycle */
109	highlow = readl(priv->base + KMB_PWM_HIGHLOW_OFFSET(pwm->hwpwm));
110	low = FIELD_GET(KMB_PWM_LOW_MASK, highlow) * NSEC_PER_SEC;
111	high = FIELD_GET(KMB_PWM_HIGH_MASK, highlow) * NSEC_PER_SEC;
112	state->duty_cycle = DIV_ROUND_UP_ULL(high, clk_rate);
113	state->period = DIV_ROUND_UP_ULL(high + low, clk_rate);
114	state->polarity = PWM_POLARITY_NORMAL;
115
116	return 0;
117}
118
119static int keembay_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
120			     const struct pwm_state *state)
121{
122	struct keembay_pwm *priv = to_keembay_pwm_dev(chip);
123	struct pwm_state current_state;
124	unsigned long long div;
125	unsigned long clk_rate;
126	u32 pwm_count = 0;
127	u16 high, low;
128
129	if (state->polarity != PWM_POLARITY_NORMAL)
130		return -EINVAL;
131
132	/*
133	 * Configure the pwm repeat count as infinite at (15:0) and leadin
134	 * low time as 0 at (30:16), which is in terms of clock cycles.
135	 */
136	keembay_pwm_update_bits(priv, KMB_PWM_LEADIN_MASK, 0,
137				KMB_PWM_LEADIN_OFFSET(pwm->hwpwm));
138
139	keembay_pwm_get_state(chip, pwm, &current_state);
140
141	if (!state->enabled) {
142		if (current_state.enabled)
143			keembay_pwm_disable(priv, pwm->hwpwm);
144		return 0;
145	}
146
147	/*
148	 * The upper 16 bits and lower 16 bits of the KMB_PWM_HIGHLOW_OFFSET
149	 * register contain the high time and low time of waveform accordingly.
150	 * All the values are in terms of clock cycles.
151	 */
152
153	clk_rate = clk_get_rate(priv->clk);
154	div = clk_rate * state->duty_cycle;
155	div = DIV_ROUND_DOWN_ULL(div, NSEC_PER_SEC);
156	if (div > KMB_PWM_COUNT_MAX)
157		return -ERANGE;
158
159	high = div;
160	div = clk_rate * state->period;
161	div = DIV_ROUND_DOWN_ULL(div, NSEC_PER_SEC);
162	div = div - high;
163	if (div > KMB_PWM_COUNT_MAX)
164		return -ERANGE;
165
166	low = div;
167
168	pwm_count = FIELD_PREP(KMB_PWM_HIGH_MASK, high) |
169		    FIELD_PREP(KMB_PWM_LOW_MASK, low);
170
171	writel(pwm_count, priv->base + KMB_PWM_HIGHLOW_OFFSET(pwm->hwpwm));
172
173	if (state->enabled && !current_state.enabled)
174		keembay_pwm_enable(priv, pwm->hwpwm);
175
176	return 0;
177}
178
179static const struct pwm_ops keembay_pwm_ops = {
180	.apply = keembay_pwm_apply,
181	.get_state = keembay_pwm_get_state,
182};
183
184static int keembay_pwm_probe(struct platform_device *pdev)
185{
186	struct device *dev = &pdev->dev;
187	struct pwm_chip *chip;
188	struct keembay_pwm *priv;
189	int ret;
190
191	chip = devm_pwmchip_alloc(dev, KMB_TOTAL_PWM_CHANNELS, sizeof(*priv));
192	if (IS_ERR(chip))
193		return PTR_ERR(chip);
194	priv = to_keembay_pwm_dev(chip);
195
196	priv->clk = devm_clk_get(dev, NULL);
197	if (IS_ERR(priv->clk))
198		return dev_err_probe(dev, PTR_ERR(priv->clk), "Failed to get clock\n");
199
200	priv->base = devm_platform_ioremap_resource(pdev, 0);
201	if (IS_ERR(priv->base))
202		return PTR_ERR(priv->base);
203
204	ret = keembay_clk_enable(dev, priv->clk);
205	if (ret)
206		return ret;
207
208	chip->ops = &keembay_pwm_ops;
209
210	ret = devm_pwmchip_add(dev, chip);
211	if (ret)
212		return dev_err_probe(dev, ret, "Failed to add PWM chip\n");
213
214	return 0;
215}
216
217static const struct of_device_id keembay_pwm_of_match[] = {
218	{ .compatible = "intel,keembay-pwm" },
219	{ }
220};
221MODULE_DEVICE_TABLE(of, keembay_pwm_of_match);
222
223static struct platform_driver keembay_pwm_driver = {
224	.probe	= keembay_pwm_probe,
225	.driver	= {
226		.name = "pwm-keembay",
227		.of_match_table = keembay_pwm_of_match,
228	},
229};
230module_platform_driver(keembay_pwm_driver);
231
232MODULE_ALIAS("platform:pwm-keembay");
233MODULE_DESCRIPTION("Intel Keem Bay PWM driver");
234MODULE_LICENSE("GPL v2");