pwm: add ep93xx PWM support

Remove the non-standard EP93xx PWM driver in drivers/misc and add
a new driver for the PWM controllers on the EP93xx platform based
on the PWM framework.

These PWM controllers each support 1 PWM channel with programmable
duty cycle, frequency, and polarity inversion.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Ryan Mallon <rmallon@gmail.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

1 files changed, 230 insertions, 0 deletions

diff --git a/drivers/pwm/pwm-ep93xx.c b/drivers/pwm/pwm-ep93xx.c
new file mode 100644
index 0000000..33aa446
--- /dev/null
+++ b/drivers/pwm/pwm-ep93xx.c
@@ -0,0 +1,230 @@
+/*
+ * PWM framework driver for Cirrus Logic EP93xx
+ *
+ * Copyright (c) 2009        Matthieu Crapet <mcrapet@gmail.com>
+ * Copyright (c) 2009, 2013  H Hartley Sweeten <hsweeten@visionengravers.com>
+ *
+ * EP9301/02 have only one channel:
+ *   platform device ep93xx-pwm.1 - PWMOUT1 (EGPIO14)
+ *
+ * EP9307 has only one channel:
+ *   platform device ep93xx-pwm.0 - PWMOUT
+ *
+ * EP9312/15 have two channels:
+ *   platform device ep93xx-pwm.0 - PWMOUT
+ *   platform device ep93xx-pwm.1 - PWMOUT1 (EGPIO14)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/pwm.h>
+
+#include <asm/div64.h>
+
+#include <mach/platform.h>	/* for ep93xx_pwm_{acquire,release}_gpio() */
+
+#define EP93XX_PWMx_TERM_COUNT	0x00
+#define EP93XX_PWMx_DUTY_CYCLE	0x04
+#define EP93XX_PWMx_ENABLE	0x08
+#define EP93XX_PWMx_INVERT	0x0c
+
+struct ep93xx_pwm {
+	void __iomem *base;
+	struct clk *clk;
+	struct pwm_chip chip;
+};
+
+static inline struct ep93xx_pwm *to_ep93xx_pwm(struct pwm_chip *chip)
+{
+	return container_of(chip, struct ep93xx_pwm, chip);
+}
+
+static int ep93xx_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct platform_device *pdev = to_platform_device(chip->dev);
+
+	return ep93xx_pwm_acquire_gpio(pdev);
+}
+
+static void ep93xx_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct platform_device *pdev = to_platform_device(chip->dev);
+
+	ep93xx_pwm_release_gpio(pdev);
+}
+
+static int ep93xx_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
+			     int duty_ns, int period_ns)
+{
+	struct ep93xx_pwm *ep93xx_pwm = to_ep93xx_pwm(chip);
+	void __iomem *base = ep93xx_pwm->base;
+	unsigned long long c;
+	unsigned long period_cycles;
+	unsigned long duty_cycles;
+	unsigned long term;
+	int ret = 0;
+
+	/*
+	 * The clock needs to be enabled to access the PWM registers.
+	 * Configuration can be changed at any time.
+	 */
+	if (!test_bit(PWMF_ENABLED, &pwm->flags)) {
+		ret = clk_enable(ep93xx_pwm->clk);
+		if (ret)
+			return ret;
+	}
+
+	c = clk_get_rate(ep93xx_pwm->clk);
+	c *= period_ns;
+	do_div(c, 1000000000);
+	period_cycles = c;
+
+	c = period_cycles;
+	c *= duty_ns;
+	do_div(c, period_ns);
+	duty_cycles = c;
+
+	if (period_cycles < 0x10000 && duty_cycles < 0x10000) {
+		term = readw(base + EP93XX_PWMx_TERM_COUNT);
+
+		/* Order is important if PWM is running */
+		if (period_cycles > term) {
+			writew(period_cycles, base + EP93XX_PWMx_TERM_COUNT);
+			writew(duty_cycles, base + EP93XX_PWMx_DUTY_CYCLE);
+		} else {
+			writew(duty_cycles, base + EP93XX_PWMx_DUTY_CYCLE);
+			writew(period_cycles, base + EP93XX_PWMx_TERM_COUNT);
+		}
+	} else {
+		ret = -EINVAL;
+	}
+
+	if (!test_bit(PWMF_ENABLED, &pwm->flags))
+		clk_disable(ep93xx_pwm->clk);
+
+	return ret;
+}
+
+static int ep93xx_pwm_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
+			       enum pwm_polarity polarity)
+{
+	struct ep93xx_pwm *ep93xx_pwm = to_ep93xx_pwm(chip);
+	int ret;
+
+	/*
+	 * The clock needs to be enabled to access the PWM registers.
+	 * Polarity can only be changed when the PWM is disabled.
+	 */
+	ret = clk_enable(ep93xx_pwm->clk);
+	if (ret)
+		return ret;
+
+	if (polarity == PWM_POLARITY_INVERSED)
+		writew(0x1, ep93xx_pwm->base + EP93XX_PWMx_INVERT);
+	else
+		writew(0x0, ep93xx_pwm->base + EP93XX_PWMx_INVERT);
+
+	clk_disable(ep93xx_pwm->clk);
+
+	return 0;
+}
+
+static int ep93xx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct ep93xx_pwm *ep93xx_pwm = to_ep93xx_pwm(chip);
+	int ret;
+
+	ret = clk_enable(ep93xx_pwm->clk);
+	if (ret)
+		return ret;
+
+	writew(0x1, ep93xx_pwm->base + EP93XX_PWMx_ENABLE);
+
+	return 0;
+}
+
+static void ep93xx_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct ep93xx_pwm *ep93xx_pwm = to_ep93xx_pwm(chip);
+
+	writew(0x0, ep93xx_pwm->base + EP93XX_PWMx_ENABLE);
+	clk_disable(ep93xx_pwm->clk);
+}
+
+static const struct pwm_ops ep93xx_pwm_ops = {
+	.request = ep93xx_pwm_request,
+	.free = ep93xx_pwm_free,
+	.config = ep93xx_pwm_config,
+	.set_polarity = ep93xx_pwm_polarity,
+	.enable = ep93xx_pwm_enable,
+	.disable = ep93xx_pwm_disable,
+	.owner = THIS_MODULE,
+};
+
+static int ep93xx_pwm_probe(struct platform_device *pdev)
+{
+	struct ep93xx_pwm *ep93xx_pwm;
+	struct resource *res;
+	int ret;
+
+	ep93xx_pwm = devm_kzalloc(&pdev->dev, sizeof(*ep93xx_pwm), GFP_KERNEL);
+	if (!ep93xx_pwm)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	ep93xx_pwm->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(ep93xx_pwm->base))
+		return PTR_ERR(ep93xx_pwm->base);
+
+	ep93xx_pwm->clk = devm_clk_get(&pdev->dev, "pwm_clk");
+	if (IS_ERR(ep93xx_pwm->clk))
+		return PTR_ERR(ep93xx_pwm->clk);
+
+	ep93xx_pwm->chip.dev = &pdev->dev;
+	ep93xx_pwm->chip.ops = &ep93xx_pwm_ops;
+	ep93xx_pwm->chip.base = -1;
+	ep93xx_pwm->chip.npwm = 1;
+
+	ret = pwmchip_add(&ep93xx_pwm->chip);
+	if (ret < 0)
+		return ret;
+
+	platform_set_drvdata(pdev, ep93xx_pwm);
+	return 0;
+}
+
+static int ep93xx_pwm_remove(struct platform_device *pdev)
+{
+	struct ep93xx_pwm *ep93xx_pwm = platform_get_drvdata(pdev);
+
+	return pwmchip_remove(&ep93xx_pwm->chip);
+}
+
+static struct platform_driver ep93xx_pwm_driver = {
+	.driver = {
+		.name = "ep93xx-pwm",
+	},
+	.probe = ep93xx_pwm_probe,
+	.remove = ep93xx_pwm_remove,
+};
+module_platform_driver(ep93xx_pwm_driver);
+
+MODULE_DESCRIPTION("Cirrus Logic EP93xx PWM driver");
+MODULE_AUTHOR("Matthieu Crapet <mcrapet@gmail.com>, "
+	      "H Hartley Sweeten <hsweeten@visionengravers.com>");
+MODULE_ALIAS("platform:ep93xx-pwm");
+MODULE_LICENSE("GPL");