--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Intel Keem Bay PWM driver
+ *
+ * Copyright (C) 2020 Intel Corporation
+ * Authors: Lai Poey Seng <poey.seng.lai@intel.com>
+ * Vineetha G. Jaya Kumaran <vineetha.g.jaya.kumaran@intel.com>
+ *
+ * Limitations:
+ * - Upon disabling a channel, the currently running
+ * period will not be completed. However, upon
+ * reconfiguration of the duty cycle/period, the
+ * currently running period will be completed first.
+ */
+
+#include <linux/bitfield.h>
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+#include <linux/regmap.h>
+
+#define KMB_TOTAL_PWM_CHANNELS 6
+#define KMB_PWM_COUNT_MAX U16_MAX
+#define KMB_PWM_EN_BIT BIT(31)
+
+/* Mask */
+#define KMB_PWM_HIGH_MASK GENMASK(31, 16)
+#define KMB_PWM_LOW_MASK GENMASK(15, 0)
+#define KMB_PWM_LEADIN_MASK GENMASK(30, 0)
+
+/* PWM Register offset */
+#define KMB_PWM_LEADIN_OFFSET(ch) (0x00 + 4 * (ch))
+#define KMB_PWM_HIGHLOW_OFFSET(ch) (0x20 + 4 * (ch))
+
+struct keembay_pwm {
+ struct pwm_chip chip;
+ struct device *dev;
+ struct clk *clk;
+ void __iomem *base;
+};
+
+static inline struct keembay_pwm *to_keembay_pwm_dev(struct pwm_chip *chip)
+{
+ return container_of(chip, struct keembay_pwm, chip);
+}
+
+static void keembay_clk_unprepare(void *data)
+{
+ clk_disable_unprepare(data);
+}
+
+static int keembay_clk_enable(struct device *dev, struct clk *clk)
+{
+ int ret;
+
+ ret = clk_prepare_enable(clk);
+ if (ret)
+ return ret;
+
+ return devm_add_action_or_reset(dev, keembay_clk_unprepare, clk);
+}
+
+static inline void keembay_pwm_update_bits(struct keembay_pwm *priv, u32 mask,
+ u32 val, u32 offset)
+{
+ u32 buff = readl(priv->base + offset);
+
+ buff = u32_replace_bits(buff, val, mask);
+ writel(buff, priv->base + offset);
+}
+
+static void keembay_pwm_enable(struct keembay_pwm *priv, int ch)
+{
+ keembay_pwm_update_bits(priv, KMB_PWM_EN_BIT, 1,
+ KMB_PWM_LEADIN_OFFSET(ch));
+}
+
+static void keembay_pwm_disable(struct keembay_pwm *priv, int ch)
+{
+ keembay_pwm_update_bits(priv, KMB_PWM_EN_BIT, 0,
+ KMB_PWM_LEADIN_OFFSET(ch));
+}
+
+static void keembay_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
+ struct pwm_state *state)
+{
+ struct keembay_pwm *priv = to_keembay_pwm_dev(chip);
+ unsigned long long high, low;
+ unsigned long clk_rate;
+ u32 highlow;
+
+ clk_rate = clk_get_rate(priv->clk);
+
+ /* Read channel enabled status */
+ highlow = readl(priv->base + KMB_PWM_LEADIN_OFFSET(pwm->hwpwm));
+ if (highlow & KMB_PWM_EN_BIT)
+ state->enabled = true;
+ else
+ state->enabled = false;
+
+ /* Read period and duty cycle */
+ highlow = readl(priv->base + KMB_PWM_HIGHLOW_OFFSET(pwm->hwpwm));
+ low = FIELD_GET(KMB_PWM_LOW_MASK, highlow) * NSEC_PER_SEC;
+ high = FIELD_GET(KMB_PWM_HIGH_MASK, highlow) * NSEC_PER_SEC;
+ state->duty_cycle = DIV_ROUND_UP_ULL(high, clk_rate);
+ state->period = DIV_ROUND_UP_ULL(high + low, clk_rate);
+ state->polarity = PWM_POLARITY_NORMAL;
+}
+
+static int keembay_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
+ const struct pwm_state *state)
+{
+ struct keembay_pwm *priv = to_keembay_pwm_dev(chip);
+ struct pwm_state current_state;
+ unsigned long long div;
+ unsigned long clk_rate;
+ u32 pwm_count = 0;
+ u16 high, low;
+
+ if (state->polarity != PWM_POLARITY_NORMAL)
+ return -EINVAL;
+
+ /*
+ * Configure the pwm repeat count as infinite at (15:0) and leadin
+ * low time as 0 at (30:16), which is in terms of clock cycles.
+ */
+ keembay_pwm_update_bits(priv, KMB_PWM_LEADIN_MASK, 0,
+ KMB_PWM_LEADIN_OFFSET(pwm->hwpwm));
+
+ keembay_pwm_get_state(chip, pwm, ¤t_state);
+
+ if (!state->enabled) {
+ if (current_state.enabled)
+ keembay_pwm_disable(priv, pwm->hwpwm);
+ return 0;
+ }
+
+ /*
+ * The upper 16 bits and lower 16 bits of the KMB_PWM_HIGHLOW_OFFSET
+ * register contain the high time and low time of waveform accordingly.
+ * All the values are in terms of clock cycles.
+ */
+
+ clk_rate = clk_get_rate(priv->clk);
+ div = clk_rate * state->duty_cycle;
+ div = DIV_ROUND_DOWN_ULL(div, NSEC_PER_SEC);
+ if (div > KMB_PWM_COUNT_MAX)
+ return -ERANGE;
+
+ high = div;
+ div = clk_rate * state->period;
+ div = DIV_ROUND_DOWN_ULL(div, NSEC_PER_SEC);
+ div = div - high;
+ if (div > KMB_PWM_COUNT_MAX)
+ return -ERANGE;
+
+ low = div;
+
+ pwm_count = FIELD_PREP(KMB_PWM_HIGH_MASK, high) |
+ FIELD_PREP(KMB_PWM_LOW_MASK, low);
+
+ writel(pwm_count, priv->base + KMB_PWM_HIGHLOW_OFFSET(pwm->hwpwm));
+
+ if (state->enabled && !current_state.enabled)
+ keembay_pwm_enable(priv, pwm->hwpwm);
+
+ return 0;
+}
+
+static const struct pwm_ops keembay_pwm_ops = {
+ .owner = THIS_MODULE,
+ .apply = keembay_pwm_apply,
+ .get_state = keembay_pwm_get_state,
+};
+
+static int keembay_pwm_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct keembay_pwm *priv;
+ int ret;
+
+ priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+
+ priv->clk = devm_clk_get(dev, NULL);
+ if (IS_ERR(priv->clk))
+ return dev_err_probe(dev, PTR_ERR(priv->clk), "Failed to get clock\n");
+
+ priv->base = devm_platform_ioremap_resource(pdev, 0);
+ if (IS_ERR(priv->base))
+ return PTR_ERR(priv->base);
+
+ ret = keembay_clk_enable(dev, priv->clk);
+ if (ret)
+ return ret;
+
+ priv->chip.base = -1;
+ priv->chip.dev = dev;
+ priv->chip.ops = &keembay_pwm_ops;
+ priv->chip.npwm = KMB_TOTAL_PWM_CHANNELS;
+
+ ret = pwmchip_add(&priv->chip);
+ if (ret)
+ return dev_err_probe(dev, ret, "Failed to add PWM chip\n");
+
+ platform_set_drvdata(pdev, priv);
+
+ return 0;
+}
+
+static int keembay_pwm_remove(struct platform_device *pdev)
+{
+ struct keembay_pwm *priv = platform_get_drvdata(pdev);
+
+ return pwmchip_remove(&priv->chip);
+}
+
+static const struct of_device_id keembay_pwm_of_match[] = {
+ { .compatible = "intel,keembay-pwm" },
+ { }
+};
+MODULE_DEVICE_TABLE(of, keembay_pwm_of_match);
+
+static struct platform_driver keembay_pwm_driver = {
+ .probe = keembay_pwm_probe,
+ .remove = keembay_pwm_remove,
+ .driver = {
+ .name = "pwm-keembay",
+ .of_match_table = keembay_pwm_of_match,
+ },
+};
+module_platform_driver(keembay_pwm_driver);
+
+MODULE_ALIAS("platform:pwm-keembay");
+MODULE_DESCRIPTION("Intel Keem Bay PWM driver");
+MODULE_LICENSE("GPL v2");
projects / linux-2.6-block.git / commitdiff