2013-10-14 21:59:15

by Hartley Sweeten

[permalink] [raw]
Subject: [PATCH] pwm: add ep93xx PWM support

Remove the non-standard EP93xx pwm driver in drivers/misc and add
a new driver for the PWM chips on the EP93xx platforms based on the
PWM framework.

These PWM chips each support 1 PWM channel with programmable duty
cycle, frequency, and polarity inversion.

Signed-off-by: H Hartley Sweeten <[email protected]>
Cc: Ryan Mallon <[email protected]>
Cc: Thierry Reding <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>

---
drivers/misc/Kconfig | 13 ---
drivers/misc/Makefile | 1 -
drivers/misc/ep93xx_pwm.c | 286 ----------------------------------------------
drivers/pwm/Kconfig | 9 ++
drivers/pwm/Makefile | 1 +
drivers/pwm/pwm-ep93xx.c | 218 +++++++++++++++++++++++++++++++++++
6 files changed, 228 insertions(+), 300 deletions(-)
delete mode 100644 drivers/misc/ep93xx_pwm.c
create mode 100644 drivers/pwm/pwm-ep93xx.c

diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index 8dacd4c..c43c66a 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -381,19 +381,6 @@ config HMC6352
This driver provides support for the Honeywell HMC6352 compass,
providing configuration and heading data via sysfs.

-config EP93XX_PWM
- tristate "EP93xx PWM support"
- depends on ARCH_EP93XX
- help
- This option enables device driver support for the PWM channels
- on the Cirrus EP93xx processors. The EP9307 chip only has one
- PWM channel all the others have two, the second channel is an
- alternate function of the EGPIO14 pin. A sysfs interface is
- provided to control the PWM channels.
-
- To compile this driver as a module, choose M here: the module will
- be called ep93xx_pwm.
-
config DS1682
tristate "Dallas DS1682 Total Elapsed Time Recorder with Alarm"
depends on I2C
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index c235d5b..ecccd00 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -33,7 +33,6 @@ obj-$(CONFIG_APDS9802ALS) += apds9802als.o
obj-$(CONFIG_ISL29003) += isl29003.o
obj-$(CONFIG_ISL29020) += isl29020.o
obj-$(CONFIG_SENSORS_TSL2550) += tsl2550.o
-obj-$(CONFIG_EP93XX_PWM) += ep93xx_pwm.o
obj-$(CONFIG_DS1682) += ds1682.o
obj-$(CONFIG_TI_DAC7512) += ti_dac7512.o
obj-$(CONFIG_C2PORT) += c2port/
diff --git a/drivers/misc/ep93xx_pwm.c b/drivers/misc/ep93xx_pwm.c
deleted file mode 100644
index cdb67a9..0000000
--- a/drivers/misc/ep93xx_pwm.c
+++ /dev/null
@@ -1,286 +0,0 @@
-/*
- * Simple PWM driver for EP93XX
- *
- * (c) Copyright 2009 Matthieu Crapet <[email protected]>
- * (c) Copyright 2009 H Hartley Sweeten <[email protected]>
- *
- * 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.
- *
- * EP9307 has only one channel:
- * - PWMOUT
- *
- * EP9301/02/12/15 have two channels:
- * - PWMOUT
- * - PWMOUT1 (alternate function for EGPIO14)
- */
-
-#include <linux/module.h>
-#include <linux/platform_device.h>
-#include <linux/slab.h>
-#include <linux/clk.h>
-#include <linux/err.h>
-#include <linux/io.h>
-
-#include <mach/platform.h>
-
-#define EP93XX_PWMx_TERM_COUNT 0x00
-#define EP93XX_PWMx_DUTY_CYCLE 0x04
-#define EP93XX_PWMx_ENABLE 0x08
-#define EP93XX_PWMx_INVERT 0x0C
-
-#define EP93XX_PWM_MAX_COUNT 0xFFFF
-
-struct ep93xx_pwm {
- void __iomem *mmio_base;
- struct clk *clk;
- u32 duty_percent;
-};
-
-/*
- * /sys/devices/platform/ep93xx-pwm.N
- * /min_freq read-only minimum pwm output frequency
- * /max_req read-only maximum pwm output frequency
- * /freq read-write pwm output frequency (0 = disable output)
- * /duty_percent read-write pwm duty cycle percent (1..99)
- * /invert read-write invert pwm output
- */
-
-static ssize_t ep93xx_pwm_get_min_freq(struct device *dev,
- struct device_attribute *attr, char *buf)
-{
- struct platform_device *pdev = to_platform_device(dev);
- struct ep93xx_pwm *pwm = platform_get_drvdata(pdev);
- unsigned long rate = clk_get_rate(pwm->clk);
-
- return sprintf(buf, "%ld\n", rate / (EP93XX_PWM_MAX_COUNT + 1));
-}
-
-static ssize_t ep93xx_pwm_get_max_freq(struct device *dev,
- struct device_attribute *attr, char *buf)
-{
- struct platform_device *pdev = to_platform_device(dev);
- struct ep93xx_pwm *pwm = platform_get_drvdata(pdev);
- unsigned long rate = clk_get_rate(pwm->clk);
-
- return sprintf(buf, "%ld\n", rate / 2);
-}
-
-static ssize_t ep93xx_pwm_get_freq(struct device *dev,
- struct device_attribute *attr, char *buf)
-{
- struct platform_device *pdev = to_platform_device(dev);
- struct ep93xx_pwm *pwm = platform_get_drvdata(pdev);
-
- if (readl(pwm->mmio_base + EP93XX_PWMx_ENABLE) & 0x1) {
- unsigned long rate = clk_get_rate(pwm->clk);
- u16 term = readl(pwm->mmio_base + EP93XX_PWMx_TERM_COUNT);
-
- return sprintf(buf, "%ld\n", rate / (term + 1));
- } else {
- return sprintf(buf, "disabled\n");
- }
-}
-
-static ssize_t ep93xx_pwm_set_freq(struct device *dev,
- struct device_attribute *attr, const char *buf, size_t count)
-{
- struct platform_device *pdev = to_platform_device(dev);
- struct ep93xx_pwm *pwm = platform_get_drvdata(pdev);
- long val;
- int err;
-
- err = kstrtol(buf, 10, &val);
- if (err)
- return -EINVAL;
-
- if (val == 0) {
- writel(0x0, pwm->mmio_base + EP93XX_PWMx_ENABLE);
- } else if (val <= (clk_get_rate(pwm->clk) / 2)) {
- u32 term, duty;
-
- val = (clk_get_rate(pwm->clk) / val) - 1;
- if (val > EP93XX_PWM_MAX_COUNT)
- val = EP93XX_PWM_MAX_COUNT;
- if (val < 1)
- val = 1;
-
- term = readl(pwm->mmio_base + EP93XX_PWMx_TERM_COUNT);
- duty = ((val + 1) * pwm->duty_percent / 100) - 1;
-
- /* If pwm is running, order is important */
- if (val > term) {
- writel(val, pwm->mmio_base + EP93XX_PWMx_TERM_COUNT);
- writel(duty, pwm->mmio_base + EP93XX_PWMx_DUTY_CYCLE);
- } else {
- writel(duty, pwm->mmio_base + EP93XX_PWMx_DUTY_CYCLE);
- writel(val, pwm->mmio_base + EP93XX_PWMx_TERM_COUNT);
- }
-
- if (!readl(pwm->mmio_base + EP93XX_PWMx_ENABLE) & 0x1)
- writel(0x1, pwm->mmio_base + EP93XX_PWMx_ENABLE);
- } else {
- return -EINVAL;
- }
-
- return count;
-}
-
-static ssize_t ep93xx_pwm_get_duty_percent(struct device *dev,
- struct device_attribute *attr, char *buf)
-{
- struct platform_device *pdev = to_platform_device(dev);
- struct ep93xx_pwm *pwm = platform_get_drvdata(pdev);
-
- return sprintf(buf, "%d\n", pwm->duty_percent);
-}
-
-static ssize_t ep93xx_pwm_set_duty_percent(struct device *dev,
- struct device_attribute *attr, const char *buf, size_t count)
-{
- struct platform_device *pdev = to_platform_device(dev);
- struct ep93xx_pwm *pwm = platform_get_drvdata(pdev);
- long val;
- int err;
-
- err = kstrtol(buf, 10, &val);
- if (err)
- return -EINVAL;
-
- if (val > 0 && val < 100) {
- u32 term = readl(pwm->mmio_base + EP93XX_PWMx_TERM_COUNT);
- u32 duty = ((term + 1) * val / 100) - 1;
-
- writel(duty, pwm->mmio_base + EP93XX_PWMx_DUTY_CYCLE);
- pwm->duty_percent = val;
- return count;
- }
-
- return -EINVAL;
-}
-
-static ssize_t ep93xx_pwm_get_invert(struct device *dev,
- struct device_attribute *attr, char *buf)
-{
- struct platform_device *pdev = to_platform_device(dev);
- struct ep93xx_pwm *pwm = platform_get_drvdata(pdev);
- int inverted = readl(pwm->mmio_base + EP93XX_PWMx_INVERT) & 0x1;
-
- return sprintf(buf, "%d\n", inverted);
-}
-
-static ssize_t ep93xx_pwm_set_invert(struct device *dev,
- struct device_attribute *attr, const char *buf, size_t count)
-{
- struct platform_device *pdev = to_platform_device(dev);
- struct ep93xx_pwm *pwm = platform_get_drvdata(pdev);
- long val;
- int err;
-
- err = kstrtol(buf, 10, &val);
- if (err)
- return -EINVAL;
-
- if (val == 0)
- writel(0x0, pwm->mmio_base + EP93XX_PWMx_INVERT);
- else if (val == 1)
- writel(0x1, pwm->mmio_base + EP93XX_PWMx_INVERT);
- else
- return -EINVAL;
-
- return count;
-}
-
-static DEVICE_ATTR(min_freq, S_IRUGO, ep93xx_pwm_get_min_freq, NULL);
-static DEVICE_ATTR(max_freq, S_IRUGO, ep93xx_pwm_get_max_freq, NULL);
-static DEVICE_ATTR(freq, S_IWUSR | S_IRUGO,
- ep93xx_pwm_get_freq, ep93xx_pwm_set_freq);
-static DEVICE_ATTR(duty_percent, S_IWUSR | S_IRUGO,
- ep93xx_pwm_get_duty_percent, ep93xx_pwm_set_duty_percent);
-static DEVICE_ATTR(invert, S_IWUSR | S_IRUGO,
- ep93xx_pwm_get_invert, ep93xx_pwm_set_invert);
-
-static struct attribute *ep93xx_pwm_attrs[] = {
- &dev_attr_min_freq.attr,
- &dev_attr_max_freq.attr,
- &dev_attr_freq.attr,
- &dev_attr_duty_percent.attr,
- &dev_attr_invert.attr,
- NULL
-};
-
-static const struct attribute_group ep93xx_pwm_sysfs_files = {
- .attrs = ep93xx_pwm_attrs,
-};
-
-static int ep93xx_pwm_probe(struct platform_device *pdev)
-{
- struct ep93xx_pwm *pwm;
- struct resource *res;
- int ret;
-
- pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
- if (!pwm)
- return -ENOMEM;
-
- pwm->clk = devm_clk_get(&pdev->dev, "pwm_clk");
- if (IS_ERR(pwm->clk))
- return PTR_ERR(pwm->clk);
-
- res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
- pwm->mmio_base = devm_ioremap_resource(&pdev->dev, res);
- if (IS_ERR(pwm->mmio_base))
- return PTR_ERR(pwm->mmio_base);
-
- ret = ep93xx_pwm_acquire_gpio(pdev);
- if (ret)
- return ret;
-
- ret = sysfs_create_group(&pdev->dev.kobj, &ep93xx_pwm_sysfs_files);
- if (ret) {
- ep93xx_pwm_release_gpio(pdev);
- return ret;
- }
-
- pwm->duty_percent = 50;
-
- /* disable pwm at startup. Avoids zero value. */
- writel(0x0, pwm->mmio_base + EP93XX_PWMx_ENABLE);
- writel(EP93XX_PWM_MAX_COUNT, pwm->mmio_base + EP93XX_PWMx_TERM_COUNT);
- writel(EP93XX_PWM_MAX_COUNT/2, pwm->mmio_base + EP93XX_PWMx_DUTY_CYCLE);
-
- clk_enable(pwm->clk);
-
- platform_set_drvdata(pdev, pwm);
- return 0;
-}
-
-static int ep93xx_pwm_remove(struct platform_device *pdev)
-{
- struct ep93xx_pwm *pwm = platform_get_drvdata(pdev);
-
- writel(0x0, pwm->mmio_base + EP93XX_PWMx_ENABLE);
- clk_disable(pwm->clk);
- sysfs_remove_group(&pdev->dev.kobj, &ep93xx_pwm_sysfs_files);
- ep93xx_pwm_release_gpio(pdev);
-
- return 0;
-}
-
-static struct platform_driver ep93xx_pwm_driver = {
- .driver = {
- .name = "ep93xx-pwm",
- .owner = THIS_MODULE,
- },
- .probe = ep93xx_pwm_probe,
- .remove = ep93xx_pwm_remove,
-};
-module_platform_driver(ep93xx_pwm_driver);
-
-MODULE_AUTHOR("Matthieu Crapet <[email protected]>, "
- "H Hartley Sweeten <[email protected]>");
-MODULE_DESCRIPTION("EP93xx PWM driver");
-MODULE_LICENSE("GPL");
-MODULE_ALIAS("platform:ep93xx-pwm");
diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index 75840b5..eece329 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -62,6 +62,15 @@ config PWM_BFIN
To compile this driver as a module, choose M here: the module
will be called pwm-bfin.

+config PWM_EP93XX
+ tristate "Cirrus Logic EP93xx PWM support"
+ depends on ARCH_EP93XX
+ help
+ Generic PWM framework driver for Cirrus Logic EP93xx.
+
+ To compile this driver as a module, choose M here: the module
+ will be called pwm-ep93xx.
+
config PWM_IMX
tristate "i.MX PWM support"
depends on ARCH_MXC
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index 77a8c18..8b754e4 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -3,6 +3,7 @@ obj-$(CONFIG_PWM_SYSFS) += sysfs.o
obj-$(CONFIG_PWM_AB8500) += pwm-ab8500.o
obj-$(CONFIG_PWM_ATMEL_TCB) += pwm-atmel-tcb.o
obj-$(CONFIG_PWM_BFIN) += pwm-bfin.o
+obj-$(CONFIG_PWM_EP93XX) += pwm-ep93xx.o
obj-$(CONFIG_PWM_IMX) += pwm-imx.o
obj-$(CONFIG_PWM_JZ4740) += pwm-jz4740.o
obj-$(CONFIG_PWM_LPC32XX) += pwm-lpc32xx.o
diff --git a/drivers/pwm/pwm-ep93xx.c b/drivers/pwm/pwm-ep93xx.c
new file mode 100644
index 0000000..43e9b60
--- /dev/null
+++ b/drivers/pwm/pwm-ep93xx.c
@@ -0,0 +1,218 @@
+/*
+ * PWM framework driver for Cirrus Logic EP93xx
+ *
+ * Copyright (C) 2013 H Hartley Sweeten <[email protected]>
+ *
+ * EP9301/02 have only one channel:
+ * platform device ep93xx-pwm.1 - PWMOUT1 (EGPIO14)
+ *
+ * EP9307 has only one channel:
+ * platform device ep93xx-pwm.0 - PWMOUT
+ *
+ * EP9312/15 have two channels:
+ * platform device ep93xx-pwm.0 - PWMOUT
+ * platform device ep93xx-pwm.1 - PWMOUT1 (EGPIO14)
+ *
+ * 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.
+ *
+ * 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.
+ */
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/pwm.h>
+
+#include <asm/div64.h>
+
+#include <mach/platform.h> /* for ep93xx_pwm_{acquire,release}_gpio() */
+
+#define EP93XX_PWMx_TERM_COUNT 0x00
+#define EP93XX_PWMx_DUTY_CYCLE 0x04
+#define EP93XX_PWMx_ENABLE 0x08
+#define EP93XX_PWMx_INVERT 0x0c
+
+struct ep93xx_pwm {
+ void __iomem *base;
+ struct clk *clk;
+ struct pwm_chip chip;
+};
+
+static inline struct ep93xx_pwm *to_ep93xx_pwm(struct pwm_chip *chip)
+{
+ return container_of(chip, struct ep93xx_pwm, chip);
+}
+
+static int ep93xx_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+ struct platform_device *pdev = to_platform_device(chip->dev);
+
+ return ep93xx_pwm_acquire_gpio(pdev);
+}
+
+static void ep93xx_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+ struct platform_device *pdev = to_platform_device(chip->dev);
+
+ ep93xx_pwm_release_gpio(pdev);
+}
+
+static int ep93xx_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
+ int duty_ns, int period_ns)
+{
+ struct ep93xx_pwm *ep93xx_pwm = to_ep93xx_pwm(chip);
+ void __iomem *base = ep93xx_pwm->base;
+ unsigned long long c;
+ unsigned long period_cycles;
+ unsigned long duty_cycles;
+ unsigned long term;
+ int ret = 0;
+
+ /*
+ * The clock needs to be enabled to access the PWM registers.
+ * Configuration can be changed at any time.
+ */
+ if (!test_bit(PWMF_ENABLED, &pwm->flags))
+ clk_enable(ep93xx_pwm->clk);
+
+ c = clk_get_rate(ep93xx_pwm->clk);
+ c *= period_ns;
+ do_div(c, 1000000000);
+ period_cycles = c;
+
+ c = period_cycles;
+ c *= duty_ns;
+ do_div(c, period_ns);
+ duty_cycles = c;
+
+ if (period_cycles < 0x10000 && duty_cycles < 0x10000) {
+ term = readw(base + EP93XX_PWMx_TERM_COUNT);
+
+ /* Order is important if PWM is running */
+ if (period_cycles > term) {
+ writew(period_cycles, base + EP93XX_PWMx_TERM_COUNT);
+ writew(duty_cycles, base + EP93XX_PWMx_DUTY_CYCLE);
+ } else {
+ writew(duty_cycles, base + EP93XX_PWMx_DUTY_CYCLE);
+ writew(period_cycles, base + EP93XX_PWMx_TERM_COUNT);
+ }
+ } else {
+ ret = -EINVAL;
+ }
+
+ if (!test_bit(PWMF_ENABLED, &pwm->flags))
+ clk_disable(ep93xx_pwm->clk);
+
+ return ret;
+}
+
+static int ep93xx_pwm_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
+ enum pwm_polarity polarity)
+{
+ struct ep93xx_pwm *ep93xx_pwm = to_ep93xx_pwm(chip);
+
+ /*
+ * The clock needs to be enabled to access the PWM registers.
+ * Polarity can only be changed when the PWM is disabled.
+ */
+ clk_enable(ep93xx_pwm->clk);
+ writew(polarity, ep93xx_pwm->base + EP93XX_PWMx_INVERT);
+ clk_disable(ep93xx_pwm->clk);
+
+ return 0;
+}
+
+static int ep93xx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+ struct ep93xx_pwm *ep93xx_pwm = to_ep93xx_pwm(chip);
+
+ clk_enable(ep93xx_pwm->clk);
+ writew(0x1, ep93xx_pwm->base + EP93XX_PWMx_ENABLE);
+
+ return 0;
+}
+
+static void ep93xx_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+ struct ep93xx_pwm *ep93xx_pwm = to_ep93xx_pwm(chip);
+
+ writew(0x0, ep93xx_pwm->base + EP93XX_PWMx_ENABLE);
+ clk_disable(ep93xx_pwm->clk);
+}
+
+static struct pwm_ops ep93xx_pwm_ops = {
+ .request = ep93xx_pwm_request,
+ .free = ep93xx_pwm_free,
+ .config = ep93xx_pwm_config,
+ .set_polarity = ep93xx_pwm_polarity,
+ .enable = ep93xx_pwm_enable,
+ .disable = ep93xx_pwm_disable,
+ .owner = THIS_MODULE,
+};
+
+static int ep93xx_pwm_probe(struct platform_device *pdev)
+{
+ struct ep93xx_pwm *ep93xx_pwm;
+ struct resource *res;
+ int ret;
+
+ ep93xx_pwm = devm_kzalloc(&pdev->dev, sizeof(*ep93xx_pwm), GFP_KERNEL);
+ if (!ep93xx_pwm)
+ return -ENOMEM;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ ep93xx_pwm->base = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(ep93xx_pwm->base))
+ return PTR_ERR(ep93xx_pwm->base);
+
+ ep93xx_pwm->clk = devm_clk_get(&pdev->dev, "pwm_clk");
+ if (IS_ERR(ep93xx_pwm->clk))
+ return PTR_ERR(ep93xx_pwm->clk);
+
+ ep93xx_pwm->chip.dev = &pdev->dev;
+ ep93xx_pwm->chip.ops = &ep93xx_pwm_ops;
+ ep93xx_pwm->chip.base = -1;
+ ep93xx_pwm->chip.npwm = 1;
+
+ ret = pwmchip_add(&ep93xx_pwm->chip);
+ if (ret < 0)
+ return ret;
+
+ platform_set_drvdata(pdev, ep93xx_pwm);
+ return 0;
+}
+
+static int ep93xx_pwm_remove(struct platform_device *pdev)
+{
+ struct ep93xx_pwm *ep93xx_pwm;
+
+ ep93xx_pwm = platform_get_drvdata(pdev);
+ if (!ep93xx_pwm)
+ return -ENODEV;
+
+ return pwmchip_remove(&ep93xx_pwm->chip);
+}
+
+static struct platform_driver ep93xx_pwm_driver = {
+ .driver = {
+ .name = "ep93xx-pwm",
+ .owner = THIS_MODULE,
+ },
+ .probe = ep93xx_pwm_probe,
+ .remove = ep93xx_pwm_remove,
+};
+module_platform_driver(ep93xx_pwm_driver);
+
+MODULE_DESCRIPTION("Cirrus Logic EP93xx PWM driver");
+MODULE_AUTHOR("H Hartley Sweeten <[email protected]>");
+MODULE_ALIAS("platform:ep93xx-pwm");
+MODULE_LICENSE("GPL");
--
1.8.3.2


2013-10-15 10:41:50

by Thierry Reding

[permalink] [raw]
Subject: Re: [PATCH] pwm: add ep93xx PWM support

On Mon, Oct 14, 2013 at 02:57:48PM -0700, H Hartley Sweeten wrote:
> Remove the non-standard EP93xx pwm driver in drivers/misc and add

pwm -> PWM

> a new driver for the PWM chips on the EP93xx platforms based on the
> PWM framework.
>
> These PWM chips each support 1 PWM channel with programmable duty

Perhaps "chips" -> "controllers"?

> cycle, frequency, and polarity inversion.
>
> Signed-off-by: H Hartley Sweeten <[email protected]>
> Cc: Ryan Mallon <[email protected]>
> Cc: Thierry Reding <[email protected]>
> Cc: Arnd Bergmann <[email protected]>
> Cc: Greg Kroah-Hartman <[email protected]>
>
> diff --git a/drivers/misc/ep93xx_pwm.c b/drivers/misc/ep93xx_pwm.c
[...]
> - * (c) Copyright 2009 Matthieu Crapet <[email protected]>
> - * (c) Copyright 2009 H Hartley Sweeten <[email protected]>
[...]
> -MODULE_AUTHOR("Matthieu Crapet <[email protected]>, "
> - "H Hartley Sweeten <[email protected]>");
[...]

> diff --git a/drivers/pwm/pwm-ep93xx.c b/drivers/pwm/pwm-ep93xx.c
[...]
> + * Copyright (C) 2013 H Hartley Sweeten <[email protected]>
[...]
> +MODULE_AUTHOR("H Hartley Sweeten <[email protected]>");

Why are you removing Matthieu from the list of authors and copyright
here? From a brief look it seems like this new driver is still based on
code from the old driver and not a complete rewrite.

> +#include <mach/platform.h> /* for ep93xx_pwm_{acquire,release}_gpio() */

I'm not sure how well that will play together with multiplatform support
but perhaps that's not an issue for ep93xx?

> +static int ep93xx_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
> +{
> + struct platform_device *pdev = to_platform_device(chip->dev);
> +
> + return ep93xx_pwm_acquire_gpio(pdev);
> +}
> +
> +static void ep93xx_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
> +{
> + struct platform_device *pdev = to_platform_device(chip->dev);
> +
> + ep93xx_pwm_release_gpio(pdev);
> +}

This looks like it would belong in the domain of pinctrl, but I suspect
that ep93xx doesn't support that.

> +static int ep93xx_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
> + int duty_ns, int period_ns)
> +{
> + struct ep93xx_pwm *ep93xx_pwm = to_ep93xx_pwm(chip);
> + void __iomem *base = ep93xx_pwm->base;
> + unsigned long long c;
> + unsigned long period_cycles;
> + unsigned long duty_cycles;
> + unsigned long term;
> + int ret = 0;
> +
> + /*
> + * The clock needs to be enabled to access the PWM registers.
> + * Configuration can be changed at any time.
> + */
> + if (!test_bit(PWMF_ENABLED, &pwm->flags))
> + clk_enable(ep93xx_pwm->clk);

clk_enable() can fail, so you should check the return value and
propagate errors.

> +static int ep93xx_pwm_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
> + enum pwm_polarity polarity)
> +{
> + struct ep93xx_pwm *ep93xx_pwm = to_ep93xx_pwm(chip);
> +
> + /*
> + * The clock needs to be enabled to access the PWM registers.
> + * Polarity can only be changed when the PWM is disabled.
> + */

Nit: the closing */ is wrongly aligned.

> + clk_enable(ep93xx_pwm->clk);

Needs a check of the return value.

> + writew(polarity, ep93xx_pwm->base + EP93XX_PWMx_INVERT);

I'd prefer if this did some explicit conversion from the PWM framework
value to the driver-specific value, even if they happen to be the same
in this case.

> +static int ep93xx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
> +{
> + struct ep93xx_pwm *ep93xx_pwm = to_ep93xx_pwm(chip);
> +
> + clk_enable(ep93xx_pwm->clk);

Also needs to check the return value.

> +static struct pwm_ops ep93xx_pwm_ops = {

static const, please.

> +static int ep93xx_pwm_remove(struct platform_device *pdev)
> +{
> + struct ep93xx_pwm *ep93xx_pwm;
> +
> + ep93xx_pwm = platform_get_drvdata(pdev);
> + if (!ep93xx_pwm)
> + return -ENODEV;

No need for this check. It will never happen.

> +
> + return pwmchip_remove(&ep93xx_pwm->chip);
> +}
> +
> +static struct platform_driver ep93xx_pwm_driver = {
> + .driver = {
> + .name = "ep93xx-pwm",
> + .owner = THIS_MODULE,

This is no longer required because the core sets it to the proper value.

> + },
> + .probe = ep93xx_pwm_probe,
> + .remove = ep93xx_pwm_remove,
> +};

Oh, and I didn't mention it before, but please get rid of all the
needless tabs for alignment. It's completely useless and doesn't help
with readability at all in my opinion.

Thierry


Attachments:
(No filename) (4.36 kB)
(No filename) (836.00 B)
Download all attachments

2013-10-16 01:22:10

by Hartley Sweeten

[permalink] [raw]
Subject: RE: [PATCH] pwm: add ep93xx PWM support

On Tuesday, October 15, 2013 3:40 AM, Thierry Reding wrote:
> On Mon, Oct 14, 2013 at 02:57:48PM -0700, H Hartley Sweeten wrote:
>> Remove the non-standard EP93xx pwm driver in drivers/misc and add
>
> pwm -> PWM

OK

>> a new driver for the PWM chips on the EP93xx platforms based on the
>> PWM framework.
>>
>> These PWM chips each support 1 PWM channel with programmable duty
>
> Perhaps "chips" -> "controllers"?

OK

>> cycle, frequency, and polarity inversion.
>>
>> Signed-off-by: H Hartley Sweeten <[email protected]>
>> Cc: Ryan Mallon <[email protected]>
>> Cc: Thierry Reding <[email protected]>
>> Cc: Arnd Bergmann <[email protected]>
>> Cc: Greg Kroah-Hartman <[email protected]>
>>
>> diff --git a/drivers/misc/ep93xx_pwm.c b/drivers/misc/ep93xx_pwm.c
> [...]
>> - * (c) Copyright 2009 Matthieu Crapet <[email protected]>
>> - * (c) Copyright 2009 H Hartley Sweeten <[email protected]>
> [...]
>> -MODULE_AUTHOR("Matthieu Crapet <[email protected]>, "
>> - "H Hartley Sweeten <[email protected]>");
> [...]
>
>> diff --git a/drivers/pwm/pwm-ep93xx.c b/drivers/pwm/pwm-ep93xx.c
> [...]
>> + * Copyright (C) 2013 H Hartley Sweeten <[email protected]>
> [...]
>> +MODULE_AUTHOR("H Hartley Sweeten <[email protected]>");
>
> Why are you removing Matthieu from the list of authors and copyright
> here? From a brief look it seems like this new driver is still based on
> code from the old driver and not a complete rewrite.

My bad. It is based on the misc driver but I forgot to put Matthieu in as
one of the original authors when I wrote it.

I'll fix that.

>> +#include <mach/platform.h> /* for ep93xx_pwm_{acquire,release}_gpio() */
>
> I'm not sure how well that will play together with multiplatform support
> but perhaps that's not an issue for ep93xx?

For multiplatform it would probably be a problem. But I don't think anyone
would be including ep93xx in a multiplatform kernel. If the problem comes up
I'll figure out some way to deal with it, probably with a pinctrl driver.

>> +static int ep93xx_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
>> +{
>> + struct platform_device *pdev = to_platform_device(chip->dev);
>> +
>> + return ep93xx_pwm_acquire_gpio(pdev);
>> +}
>> +
>> +static void ep93xx_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
>> +{
>> + struct platform_device *pdev = to_platform_device(chip->dev);
>> +
>> + ep93xx_pwm_release_gpio(pdev);
>> +}
>
> This looks like it would belong in the domain of pinctrl, but I suspect
> that ep93xx doesn't support that.

It should be but I have not worked out how to support EP93xx GPIOs with a
pinctrl driver yet. The GPIOs are pretty limited on this platform compared to
the other pinctrl users.

>> +static int ep93xx_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
>> + int duty_ns, int period_ns)
>> +{
>> + struct ep93xx_pwm *ep93xx_pwm = to_ep93xx_pwm(chip);
>> + void __iomem *base = ep93xx_pwm->base;
>> + unsigned long long c;
>> + unsigned long period_cycles;
>> + unsigned long duty_cycles;
>> + unsigned long term;
>> + int ret = 0;
>> +
>> + /*
>> + * The clock needs to be enabled to access the PWM registers.
>> + * Configuration can be changed at any time.
>> + */
>> + if (!test_bit(PWMF_ENABLED, &pwm->flags))
>> + clk_enable(ep93xx_pwm->clk);
>
> clk_enable() can fail, so you should check the return value and
> propagate errors.

I overlooked that. This will be fixed in the next version.

>> +static int ep93xx_pwm_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
>> + enum pwm_polarity polarity)
>> +{
>> + struct ep93xx_pwm *ep93xx_pwm = to_ep93xx_pwm(chip);
>> +
>> + /*
>> + * The clock needs to be enabled to access the PWM registers.
>> + * Polarity can only be changed when the PWM is disabled.
>> + */
>
> Nit: the closing */ is wrongly aligned.

OK

>> + clk_enable(ep93xx_pwm->clk);
>
> Needs a check of the return value.

OK

>> + writew(polarity, ep93xx_pwm->base + EP93XX_PWMx_INVERT);
>
> I'd prefer if this did some explicit conversion from the PWM framework
> value to the driver-specific value, even if they happen to be the same
> in this case.

OK

>> +static int ep93xx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
>> +{
>> + struct ep93xx_pwm *ep93xx_pwm = to_ep93xx_pwm(chip);
>> +
>> + clk_enable(ep93xx_pwm->clk);
>
> Also needs to check the return value.

OK

>> +static struct pwm_ops ep93xx_pwm_ops = {
>
> static const, please.

OK

>> +static int ep93xx_pwm_remove(struct platform_device *pdev)
>> +{
>> + struct ep93xx_pwm *ep93xx_pwm;
>> +
>> + ep93xx_pwm = platform_get_drvdata(pdev);
>> + if (!ep93xx_pwm)
>> + return -ENODEV;
>
> No need for this check. It will never happen.

OK

>> +
>> + return pwmchip_remove(&ep93xx_pwm->chip);
>> +}
>> +
>> +static struct platform_driver ep93xx_pwm_driver = {
>> + .driver = {
>> + .name = "ep93xx-pwm",
>> + .owner = THIS_MODULE,
>
> This is no longer required because the core sets it to the proper value.

OK

>> + },
>> + .probe = ep93xx_pwm_probe,
>> + .remove = ep93xx_pwm_remove,
>> +};
>
> Oh, and I didn't mention it before, but please get rid of all the
> needless tabs for alignment. It's completely useless and doesn't help
> with readability at all in my opinion.

Opinions differ.. But I'll remove the tabs.

Thanks for the review,
Hartley