[PATCH v2 1/4] pwm: Add support for Meson PWM Controller

[Neil Armstrong]

Add support for the PWM controller found in the Amlogic SoCs.
This driver supports the Meson8b and GXBB SoCs.

Signed-off-by: Neil Armstrong <narmstrong@xxxxxxxxxxxx>
---
 drivers/pwm/Kconfig     |   9 +
 drivers/pwm/Makefile    |   1 +
 drivers/pwm/pwm-meson.c | 491 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 501 insertions(+)
 create mode 100644 drivers/pwm/pwm-meson.c

diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index c182efc..cad5286 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -245,6 +245,15 @@ config PWM_LPSS_PLATFORM
 	  To compile this driver as a module, choose M here: the module
 	  will be called pwm-lpss-platform.
 
+config PWM_MESON
+	tristate "Amlogic Meson PWM driver"
+	depends on ARCH_MESON
+	help
+	  The platform driver for Amlogic Meson PWM controller.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called pwm-meson.
+
 config PWM_MTK_DISP
 	tristate "MediaTek display PWM driver"
 	depends on ARCH_MEDIATEK || COMPILE_TEST
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index dd35bc1..3c8843e 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -22,6 +22,7 @@ obj-$(CONFIG_PWM_LPC32XX)	+= pwm-lpc32xx.o
 obj-$(CONFIG_PWM_LPSS)		+= pwm-lpss.o
 obj-$(CONFIG_PWM_LPSS_PCI)	+= pwm-lpss-pci.o
 obj-$(CONFIG_PWM_LPSS_PLATFORM)	+= pwm-lpss-platform.o
+obj-$(CONFIG_PWM_MESON)		+= pwm-meson.o
 obj-$(CONFIG_PWM_MTK_DISP)	+= pwm-mtk-disp.o
 obj-$(CONFIG_PWM_MXS)		+= pwm-mxs.o
 obj-$(CONFIG_PWM_OMAP_DMTIMER)	+= pwm-omap-dmtimer.o
diff --git a/drivers/pwm/pwm-meson.c b/drivers/pwm/pwm-meson.c
new file mode 100644
index 0000000..9e7ecf5
--- /dev/null
+++ b/drivers/pwm/pwm-meson.c
@@ -0,0 +1,491 @@
+/*
+ * This file is provided under a dual BSD/GPLv2 license.  When using or
+ * redistributing this file, you may do so under either license.
+ *
+ * GPL LICENSE SUMMARY
+ *
+ * Copyright (c) 2016 BayLibre, SAS.
+ * Author: Neil Armstrong <narmstrong@xxxxxxxxxxxx>
+ * Copyright (C) 2014 Amlogic, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ * The full GNU General Public License is included in this distribution
+ * in the file called COPYING.
+ *
+ * BSD LICENSE
+ *
+ * Copyright (c) 2016 BayLibre, SAS.
+ * Author: Neil Armstrong <narmstrong@xxxxxxxxxxxx>
+ * Copyright (C) 2014 Amlogic, Inc.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ *   * Redistributions of source code must retain the above copyright
+ *     notice, this list of conditions and the following disclaimer.
+ *   * Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in
+ *     the documentation and/or other materials provided with the
+ *     distribution.
+ *   * Neither the name of Intel Corporation nor the names of its
+ *     contributors may be used to endorse or promote products derived
+ *     from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/clk-provider.h>
+#include <linux/platform_device.h>
+#include <linux/spinlock.h>
+#include <linux/slab.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/pwm.h>
+#include <linux/io.h>
+#include <linux/clk.h>
+#include <linux/of.h>
+
+#define REG_PWM_A	0x0
+#define REG_PWM_B	0x4
+#define PWM_HIGH_SHIFT	16
+
+#define REG_MISC_AB	0x8
+#define MISC_B_CLK_EN	BIT(23)
+#define MISC_A_CLK_EN	BIT(15)
+#define MISC_CLK_DIV_MASK	0x7f
+#define MISC_B_CLK_DIV_SHIFT	16
+#define MISC_A_CLK_DIV_SHIFT	8
+#define MISC_B_CLK_SEL_SHIFT	6
+#define MISC_A_CLK_SEL_SHIFT	4
+#define MISC_CLK_SEL_WIDTH	2
+#define MISC_B_EN	BIT(1)
+#define MISC_A_EN	BIT(0)
+
+#define PWM_NUM		2
+
+static const unsigned int mux_reg_shifts[PWM_NUM] = {
+	MISC_A_CLK_SEL_SHIFT, MISC_B_CLK_SEL_SHIFT
+};
+
+static const char * const pwm_parents[] = {
+	"xtal", "vid_pll", "fclk_div4", "fclk_div3", NULL
+};
+
+enum pwm_channel {
+	PWM_A = 0,
+	PWM_B,
+};
+
+struct meson_pwm_channel {
+	unsigned int pwm_hi;
+	unsigned int pwm_lo;
+	u8 pwm_pre_div;
+	int period;
+	int duty;
+};
+
+struct meson_pwm_chip {
+	struct platform_device *pdev;
+	struct pwm_chip chip;
+	void __iomem *base;
+	u8 inverter_mask;
+	spinlock_t lock;
+	struct clk *clk_parents[PWM_NUM];
+	struct clk_mux mux[PWM_NUM];
+	struct clk *clk[PWM_NUM];
+};
+
+#define to_meson_pwm_chip(chip) \
+	container_of(chip, struct meson_pwm_chip, chip)
+
+static int meson_pwm_calc(struct meson_pwm_chip *chip,
+			       struct meson_pwm_channel *pwm_chan,
+			       unsigned int id,
+			       int duty_ns, unsigned int period_ns)
+{
+	unsigned int pwm_pre_div;
+	unsigned int pwm_cnt;
+	unsigned int pwm_duty_cnt;
+	unsigned long fin_freq = -1;
+	unsigned long fin_ns;
+	unsigned int i = 0;
+
+	if (duty_ns > period_ns)
+		return -EINVAL;
+
+	switch (id) {
+	case PWM_A:
+		fin_freq = clk_get_rate(chip->clk[0]);
+		break;
+	case PWM_B:
+		fin_freq = clk_get_rate(chip->clk[1]);
+		break;
+	}
+	if (fin_freq <= 0) {
+		dev_err(chip->chip.dev, "invalid source clock frequency\n");
+		return -EINVAL;
+	}
+	dev_dbg(chip->chip.dev, "fin_freq: %luHz\n", fin_freq);
+	fin_ns = NSEC_PER_SEC / fin_freq;
+
+	/* Calc pre_div with the period */
+	for (i = 0; i < MISC_CLK_DIV_MASK; i++) {
+		pwm_pre_div = i;
+		pwm_cnt = DIV_ROUND_CLOSEST(period_ns,
+				fin_ns * (pwm_pre_div + 1));
+		dev_dbg(chip->chip.dev, "fin_ns=%lu pre_div=%d cnt=%d\n",
+				fin_ns, pwm_pre_div, pwm_cnt);
+		if (pwm_cnt <= 0xffff)
+			break;
+	}
+	if (i == MISC_CLK_DIV_MASK) {
+		dev_err(chip->chip.dev, "Unable to get period pre_div");
+		return -EINVAL;
+	}
+	dev_dbg(chip->chip.dev, "period_ns=%d pre_div=%d pwm_cnt=%d\n",
+		period_ns, pwm_pre_div, pwm_cnt);
+
+	if (duty_ns == period_ns) {
+		pwm_chan->pwm_pre_div = pwm_pre_div;
+		pwm_chan->pwm_hi = pwm_cnt;
+		pwm_chan->pwm_lo = 0;
+	} else if (duty_ns == 0) {
+		pwm_chan->pwm_pre_div = pwm_pre_div;
+		pwm_chan->pwm_hi = 0;
+		pwm_chan->pwm_lo = pwm_cnt;
+	} else {
+		/* Then check is we can have the duty with the same pre_div */
+		pwm_duty_cnt = DIV_ROUND_CLOSEST(duty_ns,
+					fin_ns * (pwm_pre_div + 1));
+		if (pwm_cnt > 0xffff) {
+			dev_err(chip->chip.dev, "Unable to get duty period, differences are too high");
+			return -EINVAL;
+		}
+		dev_dbg(chip->chip.dev, "duty_ns=%d pre_div=%d pwm_cnt=%d\n",
+			duty_ns, pwm_pre_div, pwm_duty_cnt);
+
+		pwm_chan->pwm_pre_div = pwm_pre_div;
+		pwm_chan->pwm_hi = pwm_duty_cnt;
+		pwm_chan->pwm_lo = pwm_cnt - pwm_chan->pwm_hi;
+	}
+
+	return 0;
+}
+
+static int meson_pwm_request(struct pwm_chip *chip,
+				  struct pwm_device *pwm)
+{
+	struct meson_pwm_channel *pwm_chan;
+
+	pwm_chan = devm_kzalloc(chip->dev, sizeof(*pwm_chan), GFP_KERNEL);
+	if (!pwm_chan)
+		return -ENOMEM;
+
+	pwm_set_chip_data(pwm, pwm_chan);
+
+	return 0;
+}
+
+static void meson_pwm_free(struct pwm_chip *chip,
+				struct pwm_device *pwm)
+{
+	devm_kfree(chip->dev, pwm_get_chip_data(pwm));
+	pwm_set_chip_data(pwm, NULL);
+}
+
+static int meson_pwm_enable(struct pwm_chip *chip,
+				 struct pwm_device *pwm)
+{
+	struct meson_pwm_chip *pwm_data = to_meson_pwm_chip(chip);
+	unsigned int id = pwm->hwpwm;
+	unsigned long flags;
+
+	spin_lock_irqsave(&pwm_data->lock, flags);
+	switch (id) {
+	case PWM_A:
+		writel(readl(pwm_data->base + REG_MISC_AB) | MISC_A_EN,
+			pwm_data->base + REG_MISC_AB);
+		break;
+
+	case PWM_B:
+		writel(readl(pwm_data->base + REG_MISC_AB) | MISC_B_EN,
+			pwm_data->base + REG_MISC_AB);
+		break;
+
+	default:
+		break;
+	}
+	spin_unlock_irqrestore(&pwm_data->lock, flags);
+
+	return 0;
+}
+
+static void meson_pwm_disable(struct pwm_chip *chip,
+				   struct pwm_device *pwm)
+{
+	struct meson_pwm_chip *pwm_data = to_meson_pwm_chip(chip);
+	unsigned int id = pwm->hwpwm;
+	unsigned long flags;
+
+	spin_lock_irqsave(&pwm_data->lock, flags);
+	switch (id) {
+	case PWM_A:
+		writel(readl(pwm_data->base + REG_MISC_AB) & ~MISC_A_EN,
+			pwm_data->base + REG_MISC_AB);
+		break;
+
+	case PWM_B:
+		writel(readl(pwm_data->base + REG_MISC_AB) & ~MISC_B_EN,
+			pwm_data->base + REG_MISC_AB);
+		break;
+
+	default:
+		break;
+	}
+	spin_unlock_irqrestore(&pwm_data->lock, flags);
+}
+
+static int meson_pwm_config(struct pwm_chip *chip,
+				 struct pwm_device *pwm,
+				 int duty_ns,
+				 int period_ns)
+{
+	struct meson_pwm_chip *pwm_data = to_meson_pwm_chip(chip);
+	struct meson_pwm_channel *pwm_chan = pwm_get_chip_data(pwm);
+	unsigned int id = pwm->hwpwm;
+	int ret;
+
+	if ((~(pwm_data->inverter_mask >> id) & 0x1))
+		duty_ns = period_ns - duty_ns;
+
+	if (period_ns == pwm_chan->period && duty_ns == pwm_chan->duty)
+		return 0;
+
+	ret = meson_pwm_calc(pwm_data, pwm_chan, id, duty_ns, period_ns);
+	if (ret) {
+		dev_err(chip->dev, "error while calculating pwm parameters\n");
+		return ret;
+	}
+
+	switch (id) {
+	case PWM_A:
+		writel((readl(pwm_data->base + REG_MISC_AB) &
+			~(MISC_CLK_DIV_MASK << MISC_A_CLK_DIV_SHIFT)) |
+			((pwm_chan->pwm_pre_div << MISC_A_CLK_DIV_SHIFT) |
+			 MISC_A_CLK_EN),
+			pwm_data->base + REG_MISC_AB);
+
+		writel((pwm_chan->pwm_hi << PWM_HIGH_SHIFT) |
+		       (pwm_chan->pwm_lo),
+		       pwm_data->base + REG_PWM_A);
+		break;
+
+	case PWM_B:
+		writel((readl(pwm_data->base + REG_MISC_AB) &
+			~(MISC_CLK_DIV_MASK << MISC_B_CLK_DIV_SHIFT)) |
+			((pwm_chan->pwm_pre_div << MISC_B_CLK_DIV_SHIFT) |
+			 MISC_B_CLK_EN),
+			pwm_data->base + REG_MISC_AB);
+
+		writel((pwm_chan->pwm_hi << PWM_HIGH_SHIFT) |
+		       (pwm_chan->pwm_lo),
+		       pwm_data->base + REG_PWM_B);
+		break;
+
+	default:
+		break;
+	}
+
+	pwm_chan->period = period_ns;
+	pwm_chan->duty = duty_ns;
+
+	return 0;
+}
+
+static int meson_pwm_set_polarity(struct pwm_chip *chip,
+				    struct pwm_device *pwm,
+				    enum pwm_polarity polarity)
+{
+	struct meson_pwm_chip *pwm_data = to_meson_pwm_chip(chip);
+	struct meson_pwm_channel *pwm_chan = pwm_get_chip_data(pwm);
+	bool invert = (polarity == PWM_POLARITY_NORMAL);
+	unsigned long flags;
+
+	spin_lock_irqsave(&pwm_data->lock, flags);
+
+	if (invert)
+		pwm_data->inverter_mask |= BIT(pwm->hwpwm);
+	else
+		pwm_data->inverter_mask &= ~BIT(pwm->hwpwm);
+
+	meson_pwm_config(chip, pwm, pwm_chan->duty, pwm_chan->period);
+
+	spin_unlock_irqrestore(&pwm_data->lock, flags);
+
+	return 0;
+}
+
+static const struct pwm_ops meson_pwm_ops = {
+	.request	= meson_pwm_request,
+	.free		= meson_pwm_free,
+	.enable		= meson_pwm_enable,
+	.disable	= meson_pwm_disable,
+	.config		= meson_pwm_config,
+	.set_polarity	= meson_pwm_set_polarity,
+	.owner		= THIS_MODULE,
+};
+
+static const struct of_device_id meson_pwm_matches[] = {
+	{ .compatible = "amlogic,meson8b-pwm", },
+	{ .compatible = "amlogic,meson-gxbb-pwm", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, meson_pwm_matches);
+
+static int meson_pwm_mux_init(struct meson_pwm_chip *chip)
+{
+	struct device *dev = &chip->pdev->dev;
+	struct clk_init_data init;
+	char clk_name[255];
+	int ret;
+	int i;
+
+	for (i = 0 ; i < PWM_NUM ; ++i) {
+		sprintf(clk_name, "%s#mux%d",
+				of_node_full_name(dev->of_node), i);
+
+		init.name = devm_kstrdup(dev, clk_name, GFP_KERNEL);
+		init.ops = &clk_mux_ops;
+		init.flags = CLK_IS_BASIC;
+		init.parent_names = pwm_parents;
+		init.num_parents = 1 << MISC_CLK_SEL_WIDTH;
+
+		chip->mux[i].reg = chip->base + REG_MISC_AB;
+		chip->mux[i].shift = mux_reg_shifts[i];
+		chip->mux[i].mask = BIT(MISC_CLK_SEL_WIDTH) - 1;
+		chip->mux[i].flags = 0;
+		chip->mux[i].lock = &chip->lock;
+		chip->mux[i].table = NULL;
+		chip->mux[i].hw.init = &init;
+
+		chip->clk[i] = devm_clk_register(dev, &chip->mux[i].hw);
+		if (IS_ERR(chip->clk[i])) {
+			dev_err(dev, "Failed to register %s\n", clk_name);
+			return PTR_ERR(chip->clk[i]);
+		}
+
+		if (chip->clk_parents[i]) {
+			ret = clk_set_parent(chip->clk[i],
+					     chip->clk_parents[i]);
+			if (ret) {
+				dev_err(dev, "Failed to set %s parent\n",
+					clk_name);
+				return ret;
+			}
+		}
+	}
+
+	return 0;
+}
+
+static int meson_pwm_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct meson_pwm_chip *chip;
+	struct resource *res;
+	int ret;
+
+	chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
+	if (chip == NULL)
+		return -ENOMEM;
+
+	chip->pdev = pdev;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	chip->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(chip->base))
+		return PTR_ERR(chip->base);
+
+	chip->clk_parents[0] = devm_clk_get(dev, "clkin0");
+	if (IS_ERR(chip->clk_parents[0])) {
+		if (PTR_ERR(chip->clk_parents[0]) == -EPROBE_DEFER)
+			return PTR_ERR(chip->clk_parents[0]);
+		chip->clk_parents[0] = NULL;
+	}
+
+	chip->clk_parents[1] = devm_clk_get(dev, "clkin1");
+	if (IS_ERR(chip->clk_parents[1])) {
+		if (PTR_ERR(chip->clk_parents[1]) == -EPROBE_DEFER)
+			return PTR_ERR(chip->clk_parents[1]);
+		chip->clk_parents[1] = NULL;
+	}
+
+	ret = meson_pwm_mux_init(chip);
+	if (ret)
+		return ret;
+
+	clk_prepare_enable(chip->clk[0]);
+	clk_prepare_enable(chip->clk[1]);
+
+	chip->chip.dev = dev;
+	chip->chip.ops = &meson_pwm_ops;
+	chip->chip.base = -1;
+	chip->chip.npwm = PWM_NUM;
+	chip->chip.of_xlate = of_pwm_xlate_with_flags;
+	chip->chip.of_pwm_n_cells = 3;
+	chip->inverter_mask = BIT(PWM_NUM) - 1;
+
+	ret = pwmchip_add(&chip->chip);
+	if (ret < 0) {
+		dev_err(dev, "failed to register PWM chip\n");
+		return ret;
+	}
+
+	platform_set_drvdata(pdev, chip);
+
+	return 0;
+}
+
+static int meson_pwm_remove(struct platform_device *pdev)
+{
+	struct meson_pwm_chip *chip = platform_get_drvdata(pdev);
+
+	return pwmchip_remove(&chip->chip);
+}
+
+static struct platform_driver meson_pwm_driver = {
+	.driver		= {
+		.name	= "meson-pwm",
+		.of_match_table = of_match_ptr(meson_pwm_matches),
+	},
+	.probe		= meson_pwm_probe,
+	.remove		= meson_pwm_remove,
+};
+module_platform_driver(meson_pwm_driver);
+
+MODULE_ALIAS("platform:meson-pwm");
+MODULE_DESCRIPTION("Amlogic Meson PWM Generator driver");
+MODULE_AUTHOR("Neil Armstrong <narmstrong@xxxxxxxxxxxx>");
+MODULE_LICENSE("Dual BSD/GPL");
-- 
2.7.0