Re: [PATCH v6 1/5] pwm: add the Berlin pwm controller driver

From: Sebastian Hesselbarth
Date: Sun Sep 20 2015 - 14:13:55 EST

On 17.09.2015 12:13, Antoine Tenart wrote:
Add a PWM controller driver for the Marvell Berlin SoCs. This PWM
controller has 4 channels.

Signed-off-by: Antoine Tenart <antoine.tenart@xxxxxxxxxxxxxxxxxx>
Acked-by: Sebastian Hesselbarth <sebastian.hesselbarth@xxxxxxxxx>

Thierry,

if you are also fine with the driver, please let me know if you want
me to take the driver through berlin-tree or if you are taking it.

I am taking the binding docs and dts changes anyway.

Sebastian

---
drivers/pwm/Kconfig | 9 ++
drivers/pwm/Makefile | 1 +
drivers/pwm/pwm-berlin.c | 229 +++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 239 insertions(+)
create mode 100644 drivers/pwm/pwm-berlin.c

diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index 062630ab7424..f3e8b7566ce5 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -92,6 +92,15 @@ config PWM_BCM2835
To compile this driver as a module, choose M here: the module
will be called pwm-bcm2835.

+config PWM_BERLIN
+ tristate "Berlin PWM support"
+ depends on ARCH_BERLIN
+ help
+ PWM framework driver for Berlin.
+
+ To compile this driver as a module, choose M here: the module
+ will be called pwm-berlin.
+
config PWM_BFIN
tristate "Blackfin PWM support"
depends on BFIN_GPTIMERS
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index a0e00c09ead3..601833d82da5 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -6,6 +6,7 @@ obj-$(CONFIG_PWM_ATMEL_HLCDC_PWM) += pwm-atmel-hlcdc.o
obj-$(CONFIG_PWM_ATMEL_TCB) += pwm-atmel-tcb.o
obj-$(CONFIG_PWM_BCM_KONA) += pwm-bcm-kona.o
obj-$(CONFIG_PWM_BCM2835) += pwm-bcm2835.o
+obj-$(CONFIG_PWM_BERLIN) += pwm-berlin.o
obj-$(CONFIG_PWM_BFIN) += pwm-bfin.o
obj-$(CONFIG_PWM_CLPS711X) += pwm-clps711x.o
obj-$(CONFIG_PWM_CRC) += pwm-crc.o
diff --git a/drivers/pwm/pwm-berlin.c b/drivers/pwm/pwm-berlin.c
new file mode 100644
index 000000000000..cb9790a2cde7
--- /dev/null
+++ b/drivers/pwm/pwm-berlin.c
@@ -0,0 +1,229 @@
+/*
+ * Marvell Berlin PWM driver
+ *
+ * Copyright (C) 2015 Marvell Technology Group Ltd.
+ *
+ * Antoine Tenart <antoine.tenart@xxxxxxxxxxxxxxxxxx>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+#include <linux/spinlock.h>
+
+#define BERLIN_PWM_EN 0x0
+#define BERLIN_PWM_CONTROL 0x4
+#define BERLIN_PWM_DUTY 0x8
+#define BERLIN_PWM_TCNT 0xc
+
+#define BERLIN_PWM_ENABLE BIT(0)
+#define BERLIN_PWM_INVERT_POLARITY BIT(3)
+#define BERLIN_PWM_PRESCALE_MASK 0x7
+#define BERLIN_PWM_PRESCALE_MAX 4096
+#define BERLIN_PWM_MAX_TCNT 65535
+
+struct berlin_pwm_chip {
+ struct pwm_chip chip;
+ struct clk *clk;
+ void __iomem *base;
+ spinlock_t lock;
+};
+
+#define to_berlin_pwm_chip(chip) \
+ container_of((chip), struct berlin_pwm_chip, chip)
+
+#define berlin_pwm_readl(chip, channel, offset) \
+ readl_relaxed((chip)->base + (channel) * 0x10 + offset)
+#define berlin_pwm_writel(val, chip, channel, offset) \
+ writel_relaxed(val, (chip)->base + (channel) * 0x10 + offset)
+
+/* prescaler table: {1, 4, 8, 16, 64, 256, 1024, 4096} */
+static const u32 prescaler_diff_table[] = {
+ 1, 4, 2, 2, 4, 4, 4, 4,
+};
+
+static int berlin_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm_dev,
+ int duty_ns, int period_ns)
+{
+ struct berlin_pwm_chip *pwm = to_berlin_pwm_chip(chip);
+ int prescale = 0;
+ u32 val, duty, period;
+ u64 cycles;
+
+ cycles = clk_get_rate(pwm->clk);
+ cycles *= period_ns;
+ do_div(cycles, NSEC_PER_SEC);
+
+ while (cycles > BERLIN_PWM_MAX_TCNT)
+ do_div(cycles, prescaler_diff_table[++prescale]);
+
+ if (cycles > BERLIN_PWM_MAX_TCNT)
+ return -EINVAL;
+
+ period = cycles;
+ cycles *= duty_ns;
+ do_div(cycles, period_ns);
+ duty = cycles;
+
+ spin_lock(&pwm->lock);
+
+ val = berlin_pwm_readl(pwm, pwm_dev->hwpwm, BERLIN_PWM_CONTROL);
+ val &= ~BERLIN_PWM_PRESCALE_MASK;
+ val |= prescale;
+ berlin_pwm_writel(val, pwm, pwm_dev->hwpwm, BERLIN_PWM_CONTROL);
+
+ berlin_pwm_writel(duty, pwm, pwm_dev->hwpwm, BERLIN_PWM_DUTY);
+ berlin_pwm_writel(period, pwm, pwm_dev->hwpwm, BERLIN_PWM_TCNT);
+
+ spin_unlock(&pwm->lock);
+
+ return 0;
+}
+
+static int berlin_pwm_set_polarity(struct pwm_chip *chip,
+ struct pwm_device *pwm_dev,
+ enum pwm_polarity polarity)
+{
+ struct berlin_pwm_chip *pwm = to_berlin_pwm_chip(chip);
+ u32 val;
+
+ spin_lock(&pwm->lock);
+
+ val = berlin_pwm_readl(pwm, pwm_dev->hwpwm, BERLIN_PWM_CONTROL);
+
+ if (polarity == PWM_POLARITY_NORMAL)
+ val &= ~BERLIN_PWM_INVERT_POLARITY;
+ else
+ val |= BERLIN_PWM_INVERT_POLARITY;
+
+ berlin_pwm_writel(val, pwm, pwm_dev->hwpwm, BERLIN_PWM_CONTROL);
+
+ spin_unlock(&pwm->lock);
+
+ return 0;
+}
+
+static int berlin_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm_dev)
+{
+ struct berlin_pwm_chip *pwm = to_berlin_pwm_chip(chip);
+ u32 val;
+
+ spin_lock(&pwm->lock);
+
+ val = berlin_pwm_readl(pwm, pwm_dev->hwpwm, BERLIN_PWM_EN);
+ val |= BERLIN_PWM_ENABLE;
+ berlin_pwm_writel(val, pwm, pwm_dev->hwpwm, BERLIN_PWM_EN);
+
+ spin_unlock(&pwm->lock);
+
+ return 0;
+}
+
+static void berlin_pwm_disable(struct pwm_chip *chip,
+ struct pwm_device *pwm_dev)
+{
+ struct berlin_pwm_chip *pwm = to_berlin_pwm_chip(chip);
+ u32 val;
+
+ spin_lock(&pwm->lock);
+
+ val = berlin_pwm_readl(pwm, pwm_dev->hwpwm, BERLIN_PWM_EN);
+ val &= ~BERLIN_PWM_ENABLE;
+ berlin_pwm_writel(val, pwm, pwm_dev->hwpwm, BERLIN_PWM_EN);
+
+ spin_unlock(&pwm->lock);
+}
+
+static const struct pwm_ops berlin_pwm_ops = {
+ .config = berlin_pwm_config,
+ .set_polarity = berlin_pwm_set_polarity,
+ .enable = berlin_pwm_enable,
+ .disable = berlin_pwm_disable,
+ .owner = THIS_MODULE,
+};
+
+static const struct of_device_id berlin_pwm_match[] = {
+ { .compatible = "marvell,berlin-pwm" },
+ { },
+};
+MODULE_DEVICE_TABLE(of, berlin_pwm_match);
+
+static int berlin_pwm_probe(struct platform_device *pdev)
+{
+ struct berlin_pwm_chip *pwm;
+ struct resource *res;
+ int ret;
+
+ pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
+ if (!pwm)
+ return -ENOMEM;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ pwm->base = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(pwm->base))
+ return PTR_ERR(pwm->base);
+
+ pwm->clk = devm_clk_get(&pdev->dev, NULL);
+ if (IS_ERR(pwm->clk))
+ return PTR_ERR(pwm->clk);
+
+ ret = clk_prepare_enable(pwm->clk);
+ if (ret)
+ return ret;
+
+ pwm->chip.dev = &pdev->dev;
+ pwm->chip.ops = &berlin_pwm_ops;
+ pwm->chip.base = -1;
+ pwm->chip.npwm = 4;
+ pwm->chip.can_sleep = true;
+ pwm->chip.of_xlate = of_pwm_xlate_with_flags;
+ pwm->chip.of_pwm_n_cells = 3;
+
+ spin_lock_init(&pwm->lock);
+
+ ret = pwmchip_add(&pwm->chip);
+ if (ret < 0) {
+ clk_disable_unprepare(pwm->clk);
+
+ dev_err(&pdev->dev, "Failed to add PWM chip: %d\n", ret);
+ return ret;
+ }
+
+ platform_set_drvdata(pdev, pwm);
+
+ return 0;
+}
+
+static int berlin_pwm_remove(struct platform_device *pdev)
+{
+ struct berlin_pwm_chip *pwm = platform_get_drvdata(pdev);
+ int ret;
+
+ ret = pwmchip_remove(&pwm->chip);
+ if (ret)
+ return ret;
+
+ clk_disable_unprepare(pwm->clk);
+ return 0;
+}
+
+static struct platform_driver berlin_pwm_driver = {
+ .probe = berlin_pwm_probe,
+ .remove = berlin_pwm_remove,
+ .driver = {
+ .name = "berlin-pwm",
+ .of_match_table = berlin_pwm_match,
+ },
+};
+module_platform_driver(berlin_pwm_driver);
+
+MODULE_AUTHOR("Antoine Tenart <antoine.tenart@xxxxxxxxxxxxxxxxxx>");
+MODULE_DESCRIPTION("Marvell Berlin PWM driver");
+MODULE_LICENSE("GPL v2");


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