Re: [PATCH 1/2] pwm: loongson1: Add PWM driver for Loongson1 SoC
From: Marcin Nowakowski
Date: Tue Feb 14 2017 - 09:56:01 EST
Hi Yang,
On 13.02.2017 16:28, Yang Ling wrote:
Add support for the PWM controller present in Loongson1 family of SoCs.
Signed-off-by: Yang Ling <gnaygnil@xxxxxxxxx>
---
drivers/pwm/Kconfig | 9 +++
drivers/pwm/Makefile | 1 +
drivers/pwm/pwm-loongson1.c | 169 ++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 179 insertions(+)
create mode 100644 drivers/pwm/pwm-loongson1.c
diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index f92dd41..985f2fe 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -216,6 +216,15 @@ config PWM_JZ4740
To compile this driver as a module, choose M here: the module
will be called pwm-jz4740.
+config PWM_LOONGSON1
+ tristate "Loongson1 PWM support"
+ depends on MACH_LOONGSON32
+ help
+ Generic PWM framework driver for Loongson1 based machines.
+
+ To compile this driver as a module, choose M here: the module
+ will be called pwm-loongson1.
+
config PWM_LP3943
tristate "TI/National Semiconductor LP3943 PWM support"
depends on MFD_LP3943
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index a48bdb5..1979453 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -19,6 +19,7 @@ obj-$(CONFIG_PWM_HIBVT) += pwm-hibvt.o
obj-$(CONFIG_PWM_IMG) += pwm-img.o
obj-$(CONFIG_PWM_IMX) += pwm-imx.o
obj-$(CONFIG_PWM_JZ4740) += pwm-jz4740.o
+obj-$(CONFIG_PWM_LOONGSON1) += pwm-loongson1.o
obj-$(CONFIG_PWM_LP3943) += pwm-lp3943.o
obj-$(CONFIG_PWM_LPC18XX_SCT) += pwm-lpc18xx-sct.o
obj-$(CONFIG_PWM_LPC32XX) += pwm-lpc32xx.o
diff --git a/drivers/pwm/pwm-loongson1.c b/drivers/pwm/pwm-loongson1.c
new file mode 100644
index 0000000..72e3fe3
--- /dev/null
+++ b/drivers/pwm/pwm-loongson1.c
@@ -0,0 +1,169 @@
+/*
+ * Copyright (c) 2017 Yang Ling <gnaygnil@xxxxxxxxx>
+ *
+ * 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.
+ */
+
+#include <linux/clk.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+#include <loongson1.h>
+
+struct ls1x_pwm_chip {
+ struct clk *clk;
+ void __iomem *base;
+ struct pwm_chip chip;
+};
+
+struct ls1x_pwm_channel {
+ u32 period_ns;
+ u32 duty_ns;
+};
+static inline struct ls1x_pwm_chip *to_ls1x_pwm_chip(struct pwm_chip *chip)
+{
+ return container_of(chip, struct ls1x_pwm_chip, chip);
+}
+
+static int ls1x_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+ struct ls1x_pwm_channel *chan = NULL;
+
+ chan = devm_kzalloc(chip->dev, sizeof(*chan), GFP_KERNEL);
+ if (!chan)
+ return -ENOMEM;
+
+ pwm_set_chip_data(pwm, chan);
+
+ return 0;
+}
+
+static void ls1x_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);
+}
+
Period and duty are stored in the pwm_device already, so you're just
duplicating the same data here. If you remove ls1x_pwm_channel then all
of the code above becomes unnecessary ...
+static int ls1x_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
+ int duty_ns, int period_ns)
+{
+ struct ls1x_pwm_chip *pc = to_ls1x_pwm_chip(chip);
+ struct ls1x_pwm_channel *chan = pwm_get_chip_data(pwm);
+ unsigned long long tmp;
+ unsigned long period, duty;
+
+ if (period_ns == chan->period_ns && duty_ns == chan->duty_ns)
+ return 0;
+
above check is already handled in pwm core
+ tmp = (unsigned long long)clk_get_rate(pc->clk) * period_ns;
+ do_div(tmp, 1000000000);
+ period = tmp;
+
+ tmp = (unsigned long long)period * duty_ns;
+ do_div(tmp, period_ns);
+ duty = period - tmp;
+
+ if (duty >= period)
+ duty = period - 1;
+
+ if (duty >> 24 || period >> 24)
+ return -EINVAL;
+
+ chan->period_ns = period_ns;
+ chan->duty_ns = duty_ns;
+
+ writel(duty, pc->base + PWM_HRC(pwm->hwpwm));
+ writel(period, pc->base + PWM_LRC(pwm->hwpwm));
+ writel(0x00, pc->base + PWM_CNT(pwm->hwpwm));
+
PWM_HRC and PWM_LRC names suggest that you're using high/low state
counters here rather than duty/period - but with no documentation I'm
just guessing here.
+ return 0;
+}
+
+static int ls1x_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+ struct ls1x_pwm_chip *pc = to_ls1x_pwm_chip(chip);
+
+ writel(CNT_RST, pc->base + PWM_CTRL(pwm->hwpwm));
+ writel(CNT_EN, pc->base + PWM_CTRL(pwm->hwpwm));
+
+ return 0;
+}
+
+static void ls1x_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+ struct ls1x_pwm_chip *pc = to_ls1x_pwm_chip(chip);
+
+ writel(PWM_OE, pc->base + PWM_CTRL(pwm->hwpwm));
+}
+
+static const struct pwm_ops ls1x_pwm_ops = {
+ .request = ls1x_pwm_request,
+ .free = ls1x_pwm_free,
+ .config = ls1x_pwm_config,
+ .enable = ls1x_pwm_enable,
+ .disable = ls1x_pwm_disable,
+ .owner = THIS_MODULE,
+};
+
+static int ls1x_pwm_probe(struct platform_device *pdev)
+{
+ struct ls1x_pwm_chip *pc = NULL;
+ struct resource *res = NULL;
+
+ pc = devm_kzalloc(&pdev->dev, sizeof(*pc), GFP_KERNEL);
+ if (!pc)
+ return -ENOMEM;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ pc->base = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(pc->base))
+ return PTR_ERR(pc->base);
+
+ pc->clk = devm_clk_get(&pdev->dev, "ls1x-pwmtimer");
+ if (IS_ERR(pc->clk)) {
+ dev_err(&pdev->dev, "failed to get %s clock\n", pdev->name);
+ return PTR_ERR(pc->clk);
+ }
+ clk_prepare_enable(pc->clk);
Should check for errors here
+ pc->chip.ops = &ls1x_pwm_ops;
+ pc->chip.dev = &pdev->dev;
+ pc->chip.base = -1;
+ pc->chip.npwm = 4;
+
+ platform_set_drvdata(pdev, pc);
+
+ return pwmchip_add(&pc->chip);
Should check for errors (and disable clk appropriately)
+}
+
+static int ls1x_pwm_remove(struct platform_device *pdev)
+{
+ struct ls1x_pwm_chip *pc = platform_get_drvdata(pdev);
+ int ret;
+
+ ret = pwmchip_remove(&pc->chip);
+ if (ret < 0)
+ return ret;
+
+ clk_disable_unprepare(pc->clk);
+
+ return 0;
+}
+
+static struct platform_driver ls1x_pwm_driver = {
+ .driver = {
+ .name = "ls1x-pwm",
+ },
+ .probe = ls1x_pwm_probe,
+ .remove = ls1x_pwm_remove,
+};
+module_platform_driver(ls1x_pwm_driver);
+
+MODULE_AUTHOR("Yang Ling <gnaygnil@xxxxxxxxx>");
+MODULE_DESCRIPTION("Loongson1 PWM driver");
+MODULE_ALIAS("platform:loongson1-pwm");
+MODULE_LICENSE("GPL");
Best regards,
Marcin