pwm: Add support for Meson PWM Controller

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@baylibre.com>
Tested-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Tested-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

3 files changed, 530 insertions, 0 deletions

diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index 80a566a..bf01288 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -262,6 +262,15 @@ 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 feef1dd..1194c54 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -24,6 +24,7 @@ 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..bfbbe7f
--- /dev/null
+++ b/drivers/pwm/pwm-meson.c
@@ -0,0 +1,520 @@
+/*
+ * 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@baylibre.com>
+ * 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@baylibre.com>
+ * 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/clk.h>
+#include <linux/clk-provider.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+#include <linux/slab.h>
+#include <linux/spinlock.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)
+
+static const unsigned int mux_reg_shifts[] = {
+	MISC_A_CLK_SEL_SHIFT,
+	MISC_B_CLK_SEL_SHIFT
+};
+
+struct meson_pwm_channel {
+	unsigned int hi;
+	unsigned int lo;
+	u8 pre_div;
+
+	struct pwm_state state;
+
+	struct clk *clk_parent;
+	struct clk_mux mux;
+	struct clk *clk;
+};
+
+struct meson_pwm_data {
+	const char * const *parent_names;
+};
+
+struct meson_pwm {
+	struct pwm_chip chip;
+	const struct meson_pwm_data *data;
+	void __iomem *base;
+	u8 inverter_mask;
+	spinlock_t lock;
+};
+
+static inline struct meson_pwm *to_meson_pwm(struct pwm_chip *chip)
+{
+	return container_of(chip, struct meson_pwm, chip);
+}
+
+static int meson_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct meson_pwm_channel *channel = pwm_get_chip_data(pwm);
+	struct device *dev = chip->dev;
+	int err;
+
+	if (!channel)
+		return -ENODEV;
+
+	if (channel->clk_parent) {
+		err = clk_set_parent(channel->clk, channel->clk_parent);
+		if (err < 0) {
+			dev_err(dev, "failed to set parent %s for %s: %d\n",
+				__clk_get_name(channel->clk_parent),
+				__clk_get_name(channel->clk), err);
+				return err;
+		}
+	}
+
+	err = clk_prepare_enable(channel->clk);
+	if (err < 0) {
+		dev_err(dev, "failed to enable clock %s: %d\n",
+			__clk_get_name(channel->clk), err);
+		return err;
+	}
+
+	chip->ops->get_state(chip, pwm, &channel->state);
+
+	return 0;
+}
+
+static void meson_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct meson_pwm_channel *channel = pwm_get_chip_data(pwm);
+
+	if (channel)
+		clk_disable_unprepare(channel->clk);
+}
+
+static int meson_pwm_calc(struct meson_pwm *meson,
+			  struct meson_pwm_channel *channel, unsigned int id,
+			  unsigned int duty, unsigned int period)
+{
+	unsigned int pre_div, cnt, duty_cnt;
+	unsigned long fin_freq = -1, fin_ns;
+
+	if (~(meson->inverter_mask >> id) & 0x1)
+		duty = period - duty;
+
+	if (period == channel->state.period &&
+	    duty == channel->state.duty_cycle)
+		return 0;
+
+	fin_freq = clk_get_rate(channel->clk);
+	if (fin_freq == 0) {
+		dev_err(meson->chip.dev, "invalid source clock frequency\n");
+		return -EINVAL;
+	}
+
+	dev_dbg(meson->chip.dev, "fin_freq: %lu Hz\n", fin_freq);
+	fin_ns = NSEC_PER_SEC / fin_freq;
+
+	/* Calc pre_div with the period */
+	for (pre_div = 0; pre_div < MISC_CLK_DIV_MASK; pre_div++) {
+		cnt = DIV_ROUND_CLOSEST(period, fin_ns * (pre_div + 1));
+		dev_dbg(meson->chip.dev, "fin_ns=%lu pre_div=%u cnt=%u\n",
+			fin_ns, pre_div, cnt);
+		if (cnt <= 0xffff)
+			break;
+	}
+
+	if (pre_div == MISC_CLK_DIV_MASK) {
+		dev_err(meson->chip.dev, "unable to get period pre_div\n");
+		return -EINVAL;
+	}
+
+	dev_dbg(meson->chip.dev, "period=%u pre_div=%u cnt=%u\n", period,
+		pre_div, cnt);
+
+	if (duty == period) {
+		channel->pre_div = pre_div;
+		channel->hi = cnt;
+		channel->lo = 0;
+	} else if (duty == 0) {
+		channel->pre_div = pre_div;
+		channel->hi = 0;
+		channel->lo = cnt;
+	} else {
+		/* Then check is we can have the duty with the same pre_div */
+		duty_cnt = DIV_ROUND_CLOSEST(duty, fin_ns * (pre_div + 1));
+		if (duty_cnt > 0xffff) {
+			dev_err(meson->chip.dev, "unable to get duty cycle\n");
+			return -EINVAL;
+		}
+
+		dev_dbg(meson->chip.dev, "duty=%u pre_div=%u duty_cnt=%u\n",
+			duty, pre_div, duty_cnt);
+
+		channel->pre_div = pre_div;
+		channel->hi = duty_cnt;
+		channel->lo = cnt - duty_cnt;
+	}
+
+	return 0;
+}
+
+static void meson_pwm_enable(struct meson_pwm *meson,
+			     struct meson_pwm_channel *channel,
+			     unsigned int id)
+{
+	u32 value, clk_shift, clk_enable, enable;
+	unsigned int offset;
+
+	switch (id) {
+	case 0:
+		clk_shift = MISC_A_CLK_DIV_SHIFT;
+		clk_enable = MISC_A_CLK_EN;
+		enable = MISC_A_EN;
+		offset = REG_PWM_A;
+		break;
+
+	case 1:
+		clk_shift = MISC_B_CLK_DIV_SHIFT;
+		clk_enable = MISC_B_CLK_EN;
+		enable = MISC_B_EN;
+		offset = REG_PWM_B;
+		break;
+	}
+
+	value = readl(meson->base + REG_MISC_AB);
+	value &= ~(MISC_CLK_DIV_MASK << clk_shift);
+	value |= channel->pre_div << clk_shift;
+	value |= clk_enable;
+	writel(value, meson->base + REG_MISC_AB);
+
+	value = (channel->hi << PWM_HIGH_SHIFT) | channel->lo;
+	writel(value, meson->base + offset);
+
+	value = readl(meson->base + REG_MISC_AB);
+	value |= enable;
+	writel(value, meson->base + REG_MISC_AB);
+}
+
+static void meson_pwm_disable(struct meson_pwm *meson, unsigned int id)
+{
+	u32 value, enable;
+
+	switch (id) {
+	case 0:
+		enable = MISC_A_EN;
+		break;
+
+	case 1:
+		enable = MISC_B_EN;
+		break;
+	}
+
+	value = readl(meson->base + REG_MISC_AB);
+	value &= ~enable;
+	writel(value, meson->base + REG_MISC_AB);
+}
+
+static int meson_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
+			   struct pwm_state *state)
+{
+	struct meson_pwm_channel *channel = pwm_get_chip_data(pwm);
+	struct meson_pwm *meson = to_meson_pwm(chip);
+	unsigned long flags;
+	int err = 0;
+
+	if (!state)
+		return -EINVAL;
+
+	spin_lock_irqsave(&meson->lock, flags);
+
+	if (!state->enabled) {
+		meson_pwm_disable(meson, pwm->hwpwm);
+		channel->state.enabled = false;
+
+		goto unlock;
+	}
+
+	if (state->period != channel->state.period ||
+	    state->duty_cycle != channel->state.duty_cycle ||
+	    state->polarity != channel->state.polarity) {
+		if (channel->state.enabled) {
+			meson_pwm_disable(meson, pwm->hwpwm);
+			channel->state.enabled = false;
+		}
+
+		if (state->polarity != channel->state.polarity) {
+			if (state->polarity == PWM_POLARITY_NORMAL)
+				meson->inverter_mask |= BIT(pwm->hwpwm);
+			else
+				meson->inverter_mask &= ~BIT(pwm->hwpwm);
+		}
+
+		err = meson_pwm_calc(meson, channel, pwm->hwpwm,
+				     state->duty_cycle, state->period);
+		if (err < 0)
+			goto unlock;
+
+		channel->state.polarity = state->polarity;
+		channel->state.period = state->period;
+		channel->state.duty_cycle = state->duty_cycle;
+	}
+
+	if (state->enabled && !channel->state.enabled) {
+		meson_pwm_enable(meson, channel, pwm->hwpwm);
+		channel->state.enabled = true;
+	}
+
+unlock:
+	spin_unlock_irqrestore(&meson->lock, flags);
+	return err;
+}
+
+static void meson_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
+				struct pwm_state *state)
+{
+	struct meson_pwm *meson = to_meson_pwm(chip);
+	u32 value, mask;
+
+	if (!state)
+		return;
+
+	switch (pwm->hwpwm) {
+	case 0:
+		mask = MISC_A_EN;
+		break;
+
+	case 1:
+		mask = MISC_B_EN;
+		break;
+	}
+
+	value = readl(meson->base + REG_MISC_AB);
+	state->enabled = (value & mask) != 0;
+}
+
+static const struct pwm_ops meson_pwm_ops = {
+	.request = meson_pwm_request,
+	.free = meson_pwm_free,
+	.apply = meson_pwm_apply,
+	.get_state = meson_pwm_get_state,
+	.owner = THIS_MODULE,
+};
+
+static const char * const pwm_meson8b_parent_names[] = {
+	"xtal", "vid_pll", "fclk_div4", "fclk_div3"
+};
+
+static const struct meson_pwm_data pwm_meson8b_data = {
+	.parent_names = pwm_meson8b_parent_names,
+};
+
+static const char * const pwm_gxbb_parent_names[] = {
+	"xtal", "hdmi_pll", "fclk_div4", "fclk_div3"
+};
+
+static const struct meson_pwm_data pwm_gxbb_data = {
+	.parent_names = pwm_gxbb_parent_names,
+};
+
+static const struct of_device_id meson_pwm_matches[] = {
+	{ .compatible = "amlogic,meson8b-pwm", .data = &pwm_meson8b_data },
+	{ .compatible = "amlogic,meson-gxbb-pwm", .data = &pwm_gxbb_data },
+	{},
+};
+MODULE_DEVICE_TABLE(of, meson_pwm_matches);
+
+static int meson_pwm_init_channels(struct meson_pwm *meson,
+				   struct meson_pwm_channel *channels)
+{
+	struct device *dev = meson->chip.dev;
+	struct device_node *np = dev->of_node;
+	struct clk_init_data init;
+	unsigned int i;
+	char name[255];
+	int err;
+
+	for (i = 0; i < meson->chip.npwm; i++) {
+		struct meson_pwm_channel *channel = &channels[i];
+
+		snprintf(name, sizeof(name), "%s#mux%u", np->full_name, i);
+
+		init.name = name;
+		init.ops = &clk_mux_ops;
+		init.flags = CLK_IS_BASIC;
+		init.parent_names = meson->data->parent_names;
+		init.num_parents = 1 << MISC_CLK_SEL_WIDTH;
+
+		channel->mux.reg = meson->base + REG_MISC_AB;
+		channel->mux.shift = mux_reg_shifts[i];
+		channel->mux.mask = BIT(MISC_CLK_SEL_WIDTH) - 1;
+		channel->mux.flags = 0;
+		channel->mux.lock = &meson->lock;
+		channel->mux.table = NULL;
+		channel->mux.hw.init = &init;
+
+		channel->clk = devm_clk_register(dev, &channel->mux.hw);
+		if (IS_ERR(channel->clk)) {
+			err = PTR_ERR(channel->clk);
+			dev_err(dev, "failed to register %s: %d\n", name, err);
+			return err;
+		}
+
+		snprintf(name, sizeof(name), "clkin%u", i);
+
+		channel->clk_parent = devm_clk_get(dev, name);
+		if (IS_ERR(channel->clk_parent)) {
+			err = PTR_ERR(channel->clk_parent);
+			if (err == -EPROBE_DEFER)
+				return err;
+
+			channel->clk_parent = NULL;
+		}
+	}
+
+	return 0;
+}
+
+static void meson_pwm_add_channels(struct meson_pwm *meson,
+				   struct meson_pwm_channel *channels)
+{
+	unsigned int i;
+
+	for (i = 0; i < meson->chip.npwm; i++)
+		pwm_set_chip_data(&meson->chip.pwms[i], &channels[i]);
+}
+
+static int meson_pwm_probe(struct platform_device *pdev)
+{
+	struct meson_pwm_channel *channels;
+	struct meson_pwm *meson;
+	struct resource *regs;
+	int err;
+
+	meson = devm_kzalloc(&pdev->dev, sizeof(*meson), GFP_KERNEL);
+	if (!meson)
+		return -ENOMEM;
+
+	regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	meson->base = devm_ioremap_resource(&pdev->dev, regs);
+	if (IS_ERR(meson->base))
+		return PTR_ERR(meson->base);
+
+	meson->chip.dev = &pdev->dev;
+	meson->chip.ops = &meson_pwm_ops;
+	meson->chip.base = -1;
+	meson->chip.npwm = 2;
+	meson->chip.of_xlate = of_pwm_xlate_with_flags;
+	meson->chip.of_pwm_n_cells = 3;
+
+	meson->data = of_device_get_match_data(&pdev->dev);
+	meson->inverter_mask = BIT(meson->chip.npwm) - 1;
+
+	channels = devm_kcalloc(&pdev->dev, meson->chip.npwm, sizeof(*meson),
+				GFP_KERNEL);
+	if (!channels)
+		return -ENOMEM;
+
+	err = meson_pwm_init_channels(meson, channels);
+	if (err < 0)
+		return err;
+
+	err = pwmchip_add(&meson->chip);
+	if (err < 0) {
+		dev_err(&pdev->dev, "failed to register PWM chip: %d\n", err);
+		return err;
+	}
+
+	meson_pwm_add_channels(meson, channels);
+
+	platform_set_drvdata(pdev, meson);
+
+	return 0;
+}
+
+static int meson_pwm_remove(struct platform_device *pdev)
+{
+	struct meson_pwm *meson = platform_get_drvdata(pdev);
+
+	return pwmchip_remove(&meson->chip);
+}
+
+static struct platform_driver meson_pwm_driver = {
+	.driver = {
+		.name = "meson-pwm",
+		.of_match_table = 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@baylibre.com>");
+MODULE_LICENSE("Dual BSD/GPL");