[PATCH 2/2] pwm: add ZTE ZX PWM device driver

Shawn Guo
2017-06-29T02:54:34Z

It adds PWM device driver for ZTE ZX family SoCs. The PWM controller
supports 4 devices with polarity configuration.

The driver has been tested with pwm-regulator support to scale core
voltage via cpufreq.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
---
drivers/pwm/Kconfig | 9 ++
drivers/pwm/Makefile | 1 +
drivers/pwm/pwm-zx.c | 244 +++++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 254 insertions(+)
create mode 100644 drivers/pwm/pwm-zx.c

diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index 313c10789ca2..e98175331a69 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -500,4 +500,13 @@ config PWM_VT8500
To compile this driver as a module, choose M here: the module
will be called pwm-vt8500.

+config PWM_ZX
+ tristate "ZTE ZX PWM support"
+ depends on ARCH_ZX
+ help
+ Generic PWM framework driver for ZTE ZX family SoCs.
+
+ To compile this driver as a module, choose M here: the module
+ will be called pwm-zx.
+
endif
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index 93da1f79a3b8..75ab74094d7b 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -49,3 +49,4 @@ obj-$(CONFIG_PWM_TIPWMSS) += pwm-tipwmss.o
obj-$(CONFIG_PWM_TWL) += pwm-twl.o
obj-$(CONFIG_PWM_TWL_LED) += pwm-twl-led.o
obj-$(CONFIG_PWM_VT8500) += pwm-vt8500.o
+obj-$(CONFIG_PWM_ZX) += pwm-zx.o
diff --git a/drivers/pwm/pwm-zx.c b/drivers/pwm/pwm-zx.c
new file mode 100644
index 000000000000..5c81c2ddc0a9
--- /dev/null
+++ b/drivers/pwm/pwm-zx.c
@@ -0,0 +1,244 @@
+/*
+ * Copyright (C) 2017 Sanechips Technology Co., Ltd.
+ * Copyright 2017 Linaro Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+#include <linux/slab.h>
+
+#define ZX_PWM_MODE 0x0
+#define ZX_PWM_CLKDIV_MASK GENMASK(11, 2)
+#define ZX_PWM_CLKDIV(x) (((x) << 8) & ZX_PWM_CLKDIV_MASK)
+#define ZX_PWM_POLAR BIT(1)
+#define ZX_PWM_EN BIT(0)
+#define ZX_PWM_PERIOD 0x4
+#define ZX_PWM_DUTY 0x8
+
+#define ZX_PWM_CLKDIV_MAX 1023
+#define ZX_PWM_PERIOD_MAX 65535
+
+struct zx_pwm_chip {
+ struct pwm_chip chip;
+ struct clk *pclk;
+ struct clk *wclk;
+ void __iomem *base;
+};
+
+#define to_zx_pwm_chip(_chip) container_of(_chip, struct zx_pwm_chip, chip)
+
+static inline u32 zx_pwm_readl(struct zx_pwm_chip *zpc, unsigned int hwpwm,
+ unsigned int offset)
+{
+ return readl(zpc->base + (hwpwm + 1) * 0x10 + offset);
+}
+
+static inline void zx_pwm_writel(struct zx_pwm_chip *zpc, unsigned int hwpwm,
+ unsigned int offset, u32 val)
+{
+ writel(val, zpc->base + (hwpwm + 1) * 0x10 + offset);
+}
+
+static int zx_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
+ int duty_ns, int period_ns)
+{
+ struct zx_pwm_chip *zpc = to_zx_pwm_chip(chip);
+ unsigned int period_cycles;
+ unsigned int duty_cycles;
+ unsigned long long c;
+ unsigned long rate;
+ int div = 1;
+ u32 val;
+
+ /* Find out the best divider */
+ rate = clk_get_rate(zpc->wclk);
+ while (1) {
+ c = rate / div;
+ c = c * period_ns;
+ do_div(c, NSEC_PER_SEC);
+ if (c < ZX_PWM_PERIOD_MAX)
+ break;
+ div++;
+ if (div > ZX_PWM_CLKDIV_MAX)
+ return -ERANGE;
+ }
+
+ /* Calculate duty cycles */
+ period_cycles = c;
+ c *= duty_ns;
+ do_div(c, period_ns);
+ duty_cycles = c;
+
+ /*
+ * If the pwm is being enabled, we have to temporarily disable it
+ * before configuring the registers.
+ */
+ if (pwm_is_enabled(pwm)) {
+ val = zx_pwm_readl(zpc, pwm->hwpwm, ZX_PWM_MODE);
+ val &= ~ZX_PWM_EN;
+ zx_pwm_writel(zpc, pwm->hwpwm, ZX_PWM_MODE, val);
+ }
+
+ /* Set up registers */
+ val = zx_pwm_readl(zpc, pwm->hwpwm, ZX_PWM_MODE);
+ val &= ZX_PWM_CLKDIV_MASK;
+ val |= ZX_PWM_CLKDIV(div);
+ zx_pwm_writel(zpc, pwm->hwpwm, ZX_PWM_MODE, val);
+
+ zx_pwm_writel(zpc, pwm->hwpwm, ZX_PWM_PERIOD, period_cycles);
+ zx_pwm_writel(zpc, pwm->hwpwm, ZX_PWM_DUTY, duty_cycles);
+
+ /* Re-enable the pwm if needed */
+ if (pwm_is_enabled(pwm)) {
+ val = zx_pwm_readl(zpc, pwm->hwpwm, ZX_PWM_MODE);
+ val |= ZX_PWM_EN;
+ zx_pwm_writel(zpc, pwm->hwpwm, ZX_PWM_MODE, val);
+ }
+
+ return 0;
+}
+
+static int zx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+ struct zx_pwm_chip *zpc = to_zx_pwm_chip(chip);
+ u32 val;
+ int ret;
+
+ ret = clk_prepare_enable(zpc->wclk);
+ if (ret)
+ return ret;
+
+ /* Enable the pwm */
+ val = zx_pwm_readl(zpc, pwm->hwpwm, ZX_PWM_MODE);
+ val |= ZX_PWM_EN;
+ zx_pwm_writel(zpc, pwm->hwpwm, ZX_PWM_MODE, val);
+
+ return 0;
+}
+
+static void zx_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+ struct zx_pwm_chip *zpc = to_zx_pwm_chip(chip);
+ u32 val;
+
+ /* Disable the pwm */
+ val = zx_pwm_readl(zpc, pwm->hwpwm, ZX_PWM_MODE);
+ val &= ~ZX_PWM_EN;
+ zx_pwm_writel(zpc, pwm->hwpwm, ZX_PWM_MODE, val);
+
+ clk_disable_unprepare(zpc->wclk);
+}
+
+static int zx_pwm_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
+ enum pwm_polarity polarity)
+{
+ struct zx_pwm_chip *zpc = to_zx_pwm_chip(chip);
+ u32 val;
+
+ val = zx_pwm_readl(zpc, pwm->hwpwm, ZX_PWM_MODE);
+
+ if (polarity == PWM_POLARITY_INVERSED)
+ val &= ~ZX_PWM_POLAR;
+ else
+ val |= ZX_PWM_POLAR;
+
+ zx_pwm_writel(zpc, pwm->hwpwm, ZX_PWM_MODE, val);
+
+ return 0;
+}
+
+static const struct pwm_ops zx_pwm_ops = {
+ .config = zx_pwm_config,
+ .enable = zx_pwm_enable,
+ .disable = zx_pwm_disable,
+ .set_polarity = zx_pwm_set_polarity,
+ .owner = THIS_MODULE,
+};
+
+static int zx_pwm_probe(struct platform_device *pdev)
+{
+ struct zx_pwm_chip *zpc;
+ struct resource *res;
+ int ret;
+
+ zpc = devm_kzalloc(&pdev->dev, sizeof(*zpc), GFP_KERNEL);
+ if (!zpc)
+ return -ENOMEM;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ zpc->base = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(zpc->base))
+ return PTR_ERR(zpc->base);
+
+ zpc->pclk = devm_clk_get(&pdev->dev, "pclk");
+ if (IS_ERR(zpc->pclk))
+ return PTR_ERR(zpc->pclk);
+
+ zpc->wclk = devm_clk_get(&pdev->dev, "wclk");
+ if (IS_ERR(zpc->wclk))
+ return PTR_ERR(zpc->wclk);
+
+ zpc->chip.dev = &pdev->dev;
+ zpc->chip.ops = &zx_pwm_ops;
+ zpc->chip.base = -1;
+ zpc->chip.npwm = 4;
+ zpc->chip.of_xlate = of_pwm_xlate_with_flags;
+ zpc->chip.of_pwm_n_cells = 3;
+
+ ret = pwmchip_add(&zpc->chip);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "failed to add pwm chip %d\n", ret);
+ return ret;
+ }
+
+ platform_set_drvdata(pdev, zpc);
+
+ ret = clk_prepare_enable(zpc->pclk);
+ if (ret)
+ goto pwm_remove;
+
+ return 0;
+
+pwm_remove:
+ pwmchip_remove(&zpc->chip);
+ return ret;
+}
+
+static int zx_pwm_remove(struct platform_device *pdev)
+{
+ struct zx_pwm_chip *zpc = platform_get_drvdata(pdev);
+
+ clk_disable_unprepare(zpc->pclk);
+
+ return pwmchip_remove(&zpc->chip);
+}
+
+static const struct of_device_id zx_pwm_dt_ids[] = {
+ { .compatible = "zte,zx296718-pwm", },
+ { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, zx_pwm_dt_ids);
+
+static struct platform_driver zx_pwm_driver = {
+ .driver = {
+ .name = "zx-pwm",
+ .of_match_table = zx_pwm_dt_ids,
+ },
+ .probe = zx_pwm_probe,
+ .remove = zx_pwm_remove,
+};
+module_platform_driver(zx_pwm_driver);
+
+MODULE_ALIAS("platform:zx-pwm");
+MODULE_AUTHOR("Shawn Guo <shawn.guo@linaro.org>");
+MODULE_DESCRIPTION("ZTE ZX PWM Driver");
+MODULE_LICENSE("GPL v2");
--
1.9.1