1 files changed, 158 insertions, 0 deletions
diff --git a/drivers/clk/clk-pwm.c b/drivers/clk/clk-pwm.c
new file mode 100644
index 000000000..da2c8eddf
--- /dev/null
+++ b/drivers/clk/clk-pwm.c
@@ -0,0 +1,158 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2014 Philipp Zabel, Pengutronix
+ *
+ * PWM (mis)used as clock output
+ */
+#include <linux/clk-provider.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+
+struct clk_pwm {
+	struct clk_hw hw;
+	struct pwm_device *pwm;
+	u32 fixed_rate;
+};
+
+static inline struct clk_pwm *to_clk_pwm(struct clk_hw *hw)
+{
+	return container_of(hw, struct clk_pwm, hw);
+}
+
+static int clk_pwm_prepare(struct clk_hw *hw)
+{
+	struct clk_pwm *clk_pwm = to_clk_pwm(hw);
+
+	return pwm_enable(clk_pwm->pwm);
+}
+
+static void clk_pwm_unprepare(struct clk_hw *hw)
+{
+	struct clk_pwm *clk_pwm = to_clk_pwm(hw);
+
+	pwm_disable(clk_pwm->pwm);
+}
+
+static unsigned long clk_pwm_recalc_rate(struct clk_hw *hw,
+					 unsigned long parent_rate)
+{
+	struct clk_pwm *clk_pwm = to_clk_pwm(hw);
+
+	return clk_pwm->fixed_rate;
+}
+
+static int clk_pwm_get_duty_cycle(struct clk_hw *hw, struct clk_duty *duty)
+{
+	struct clk_pwm *clk_pwm = to_clk_pwm(hw);
+	struct pwm_state state;
+
+	pwm_get_state(clk_pwm->pwm, &state);
+
+	duty->num = state.duty_cycle;
+	duty->den = state.period;
+
+	return 0;
+}
+
+static const struct clk_ops clk_pwm_ops = {
+	.prepare = clk_pwm_prepare,
+	.unprepare = clk_pwm_unprepare,
+	.recalc_rate = clk_pwm_recalc_rate,
+	.get_duty_cycle = clk_pwm_get_duty_cycle,
+};
+
+static int clk_pwm_probe(struct platform_device *pdev)
+{
+	struct device_node *node = pdev->dev.of_node;
+	struct clk_init_data init;
+	struct clk_pwm *clk_pwm;
+	struct pwm_device *pwm;
+	struct pwm_args pargs;
+	const char *clk_name;
+	int ret;
+
+	clk_pwm = devm_kzalloc(&pdev->dev, sizeof(*clk_pwm), GFP_KERNEL);
+	if (!clk_pwm)
+		return -ENOMEM;
+
+	pwm = devm_pwm_get(&pdev->dev, NULL);
+	if (IS_ERR(pwm))
+		return PTR_ERR(pwm);
+
+	pwm_get_args(pwm, &pargs);
+	if (!pargs.period) {
+		dev_err(&pdev->dev, "invalid PWM period\n");
+		return -EINVAL;
+	}
+
+	if (of_property_read_u32(node, "clock-frequency", &clk_pwm->fixed_rate))
+		clk_pwm->fixed_rate = div64_u64(NSEC_PER_SEC, pargs.period);
+
+	if (!clk_pwm->fixed_rate) {
+		dev_err(&pdev->dev, "fixed_rate cannot be zero\n");
+		return -EINVAL;
+	}
+
+	if (pargs.period != NSEC_PER_SEC / clk_pwm->fixed_rate &&
+	    pargs.period != DIV_ROUND_UP(NSEC_PER_SEC, clk_pwm->fixed_rate)) {
+		dev_err(&pdev->dev,
+			"clock-frequency does not match PWM period\n");
+		return -EINVAL;
+	}
+
+	/*
+	 * FIXME: pwm_apply_args() should be removed when switching to the
+	 * atomic PWM API.
+	 */
+	pwm_apply_args(pwm);
+	ret = pwm_config(pwm, (pargs.period + 1) >> 1, pargs.period);
+	if (ret < 0)
+		return ret;
+
+	clk_name = node->name;
+	of_property_read_string(node, "clock-output-names", &clk_name);
+
+	init.name = clk_name;
+	init.ops = &clk_pwm_ops;
+	init.flags = 0;
+	init.num_parents = 0;
+
+	clk_pwm->pwm = pwm;
+	clk_pwm->hw.init = &init;
+	ret = devm_clk_hw_register(&pdev->dev, &clk_pwm->hw);
+	if (ret)
+		return ret;
+
+	return of_clk_add_hw_provider(node, of_clk_hw_simple_get, &clk_pwm->hw);
+}
+
+static int clk_pwm_remove(struct platform_device *pdev)
+{
+	of_clk_del_provider(pdev->dev.of_node);
+
+	return 0;
+}
+
+static const struct of_device_id clk_pwm_dt_ids[] = {
+	{ .compatible = "pwm-clock" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, clk_pwm_dt_ids);
+
+static struct platform_driver clk_pwm_driver = {
+	.probe = clk_pwm_probe,
+	.remove = clk_pwm_remove,
+	.driver = {
+		.name = "pwm-clock",
+		.of_match_table = clk_pwm_dt_ids,
+	},
+};
+
+module_platform_driver(clk_pwm_driver);
+
+MODULE_AUTHOR("Philipp Zabel <p.zabel@pengutronix.de>");
+MODULE_DESCRIPTION("PWM clock driver");
+MODULE_LICENSE("GPL");