Re: [PATCH v2 1/6] hwmon: (gxp-fan-ctrl) Add GXP fan controller
From: Guenter Roeck
Date: Mon Nov 28 2022 - 23:02:45 EST
On Mon, Nov 28, 2022 at 05:02:14PM -0600, nick.hawkins@xxxxxxx wrote:
> From: Nick Hawkins <nick.hawkins@xxxxxxx>
>
> The GXP SoC can support up to 16 fans through the interface provided by
> the CPLD. The current support is limited to 8 fans. The fans speeds are
> controlled via 8 different PWMs which can vary in value from 0-255. The
> fans are also capable of reporting if they have failed to the CPLD which
> in turn reports the status to the GXP SoC.
>
> Signed-off-by: Nick Hawkins <nick.hawkins@xxxxxxx>
> ---
>
> v2:
> *Changed number of supported fans from 16 to 8 in code
> *Remove last sentence of commit description
> *Removed support for fan[0-15]_input in code and documentation
> *Changed documentation to limit fan count to 7
> *Changed documentation license
> *Removed PWM defines
> *Added gxp-fan-ctrl to hwmon's index.rst
> *Removed mutex
> *Added fan_enable support to report if the fan is enabled
> *Changed presents to present
> *Removed unnecessary ()
> *Add comment for plreg reads and calculations
> *Add comment for the use of platform power state in code
> *Removed use of variable offsets and went with hardcoding instead
> *Rewrote driver to use devm_hwmon_device_register_with_info()
> *Remove unused header files
> *Fix GPL header
> *Changed module description
> *Add kfree in case of failure to get regmaps or resource
> ---
> Documentation/hwmon/gxp-fan-ctrl.rst | 28 +++
> Documentation/hwmon/index.rst | 1 +
> drivers/hwmon/Kconfig | 9 +
> drivers/hwmon/Makefile | 1 +
> drivers/hwmon/gxp-fan-ctrl.c | 305 +++++++++++++++++++++++++++
> 5 files changed, 344 insertions(+)
> create mode 100644 Documentation/hwmon/gxp-fan-ctrl.rst
> create mode 100644 drivers/hwmon/gxp-fan-ctrl.c
>
> diff --git a/Documentation/hwmon/gxp-fan-ctrl.rst b/Documentation/hwmon/gxp-fan-ctrl.rst
> new file mode 100644
> index 000000000000..ae3397e81c04
> --- /dev/null
> +++ b/Documentation/hwmon/gxp-fan-ctrl.rst
> @@ -0,0 +1,28 @@
> +.. SPDX-License-Identifier: GPL-2.0-only
> +
> +Kernel driver gxp-fan-ctrl
> +==========================
> +
> +Supported chips:
> +
> + * HPE GXP SOC
> +
> +Author: Nick Hawkins <nick.hawkins@xxxxxxx>
> +
> +
> +Description
> +-----------
> +
> +gxp-fan-ctrl is a driver which provides fan control for the hpe gxp soc.
> +The driver allows the gathering of fan status and the use of fan
> +PWM control.
> +
> +
> +Sysfs attributes
> +----------------
> +
> +======================= ===========================================================
> +pwm[0-7] Fan 0 to 7 respective PWM value (0-255)
> +fan[0-7]_fault Fan 0 to 7 respective fault status: 1 fail, 0 ok
> +fan[0-7]_enable Fan 0 to 7 respective enabled status: 1 enabled, 0 disabled
> +======================= ===========================================================
> diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
> index f7113b0f8b2a..b319ab173d1d 100644
> --- a/Documentation/hwmon/index.rst
> +++ b/Documentation/hwmon/index.rst
> @@ -73,6 +73,7 @@ Hardware Monitoring Kernel Drivers
> g762
> gsc-hwmon
> gl518sm
> + gxp-fan-ctrl
> hih6130
> ibmaem
> ibm-cffps
> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> index e70d9614bec2..9e0427f20141 100644
> --- a/drivers/hwmon/Kconfig
> +++ b/drivers/hwmon/Kconfig
> @@ -705,6 +705,15 @@ config SENSORS_GPIO_FAN
> This driver can also be built as a module. If so, the module
> will be called gpio-fan.
>
> +config SENSORS_GXP_FAN_CTRL
> + tristate "HPE GXP fan controller"
> + depends on ARCH_HPE_GXP || COMPILE_TEST
> + help
> + If you say yes here you get support for GXP fan control functionality.
> +
> + The GXP controls fan function via the CPLD through the use of PWM
> + registers. This driver reports status and pwm setting of the fans.
> +
> config SENSORS_HIH6130
> tristate "Honeywell Humidicon HIH-6130 humidity/temperature sensor"
> depends on I2C
> diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
> index 007e829d1d0d..b474dcc708c4 100644
> --- a/drivers/hwmon/Makefile
> +++ b/drivers/hwmon/Makefile
> @@ -83,6 +83,7 @@ obj-$(CONFIG_SENSORS_GL518SM) += gl518sm.o
> obj-$(CONFIG_SENSORS_GL520SM) += gl520sm.o
> obj-$(CONFIG_SENSORS_GSC) += gsc-hwmon.o
> obj-$(CONFIG_SENSORS_GPIO_FAN) += gpio-fan.o
> +obj-$(CONFIG_SENSORS_GXP_FAN_CTRL) += gxp-fan-ctrl.o
> obj-$(CONFIG_SENSORS_HIH6130) += hih6130.o
> obj-$(CONFIG_SENSORS_ULTRA45) += ultra45_env.o
> obj-$(CONFIG_SENSORS_I5500) += i5500_temp.o
> diff --git a/drivers/hwmon/gxp-fan-ctrl.c b/drivers/hwmon/gxp-fan-ctrl.c
> new file mode 100644
> index 000000000000..0b03d33a3a7b
> --- /dev/null
> +++ b/drivers/hwmon/gxp-fan-ctrl.c
> @@ -0,0 +1,305 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/* Copyright (C) 2022 Hewlett-Packard Enterprise Development Company, L.P. */
> +
> +#include <linux/err.h>
> +#include <linux/hwmon.h>
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +#include <linux/slab.h>
> +
> +#define OFS_FAN_INST 0 /* Is 0 because plreg base will be set at INST */
> +#define OFS_FAN_FAIL 2 /* Is 2 bytes after base */
> +#define OFS_SEVSTAT 0 /* Is 0 because fn2 base will be set at SEVSTAT */
> +#define POWER_BIT 24
> +
> +struct gxp_fan_ctrl_drvdata {
> + struct device *dev;
> + struct device *hwmon_dev;
Both dev and hwmon_dev are unused and thus pointless.
> + struct regmap *plreg_map; /* Programmable logic register regmap */
> + struct regmap *fn2_map; /* Function 2 regmap */
> + void __iomem *base;
> +};
> +
> +static bool fan_installed(struct device *dev, int fan)
> +{
> + struct gxp_fan_ctrl_drvdata *drvdata = dev_get_drvdata(dev);
> + u32 val;
> +
> + regmap_read(drvdata->plreg_map, OFS_FAN_INST, &val);
> + if (val & BIT(fan))
> + return 1;
> + else
> + return 0;
else after return is unnecessary, and
return !!(val & BIT(fan));
would avoid the conditional.
> +}
> +
> +static long fan_failed(struct device *dev, int fan)
> +{
> + struct gxp_fan_ctrl_drvdata *drvdata = dev_get_drvdata(dev);
> + u32 val;
> +
> + /*
> + * The offset for fan fail is 2 which is not word aligned.
> + * Read from fan installed which is 0 and shift value.
> + */
> +
> + regmap_read(drvdata->plreg_map, OFS_FAN_INST, &val);
> +
> + if ((val >> (8 * OFS_FAN_FAIL)) & BIT(fan))
> + return 1;
> + else
> + return 0;
else after return is pointless, and this can be written as
return !!((val >> (8 * OFS_FAN_FAIL)) & BIT(fan));
to avoid the conditional.
> +}
> +
> +static long fan_enabled(struct device *dev, int fan)
> +{
> + struct gxp_fan_ctrl_drvdata *drvdata = dev_get_drvdata(dev);
> + unsigned int reg;
> +
> + /*
> + * Check the power status as if the platform is off the value
> + * reported for the PWM will be incorrect. Report fan as
> + * disabled.
> + */
> + regmap_read(drvdata->fn2_map, OFS_SEVSTAT, ®);
> +
> + /* If Fan is installed and the system is on it is enabled */
> + if ((reg & BIT(POWER_BIT)) && fan_installed(dev, fan))
> + return 1;
> +
> + /* Platform power is off, fan is disabled */
> + return 0;
Same as above.
> +}
> +
> +static int gxp_pwm_write(struct device *dev, u32 attr, int channel, long val)
> +{
> + struct gxp_fan_ctrl_drvdata *drvdata = dev_get_drvdata(dev);
> +
> + switch (attr) {
> + case hwmon_pwm_input:
> + if (val > 255)
> + return -EINVAL;
Should also check for values < 0.
> + writeb(val, drvdata->base + channel);
The mixed use of direct writes and regmap is odd and confusing.
Why use regmap for plreg_map and for fn2_map but not for base ?
Can this be unified ? If not, why ?
> + return 0;
> + default:
> + return -EOPNOTSUPP;
> + }
> +}
> +
> +static int gxp_fan_ctrl_write(struct device *dev, enum hwmon_sensor_types type,
> + u32 attr, int channel, long val)
> +{
> + switch (type) {
> + case hwmon_pwm:
> + return gxp_pwm_write(dev, attr, channel, val);
> + default:
> + return -EOPNOTSUPP;
> + }
> +}
> +
> +static int gxp_fan_read(struct device *dev, u32 attr, int channel, long *val)
> +{
> + switch (attr) {
> + case hwmon_fan_enable:
> + *val = fan_enabled(dev, channel);
> + return 0;
> + case hwmon_fan_fault:
> + *val = fan_failed(dev, channel);
> + return 0;
> + default:
> + return -EOPNOTSUPP;
> + }
> +}
> +
> +static int gxp_pwm_read(struct device *dev, u32 attr, int channel, long *val)
> +{
> + struct gxp_fan_ctrl_drvdata *drvdata = dev_get_drvdata(dev);
> + unsigned int reg;
> +
> + /*
> + * Check the power status of the platform. If the platform is off
> + * the value reported for the PWM will be incorrect. In this case
> + * report a PWM of zero.
> + */
> + regmap_read(drvdata->fn2_map, 0, ®);
> + if (reg & BIT(POWER_BIT)) {
> + /* If Fan present, then read it. */
> + *val = fan_installed(dev, channel) ? readb(drvdata->base + channel) : 0;
> + } else {
> + *val = 0;
> + }
> +
> + return 0;
> +}
> +
> +static int gxp_fan_ctrl_read(struct device *dev, enum hwmon_sensor_types type,
> + u32 attr, int channel, long *val)
> +{
> + switch (type) {
> + case hwmon_fan:
> + return gxp_fan_read(dev, attr, channel, val);
> + case hwmon_pwm:
> + return gxp_pwm_read(dev, attr, channel, val);
> + default:
> + return -EOPNOTSUPP;
> + }
> +}
> +
> +static umode_t gxp_fan_ctrl_is_visible(const void *_data,
> + enum hwmon_sensor_types type,
> + u32 attr, int channel)
> +{
> + umode_t mode = 0;
> +
> + switch (type) {
> + case hwmon_fan:
> + switch (attr) {
> + case hwmon_fan_enable:
> + case hwmon_fan_fault:
> + mode = 0444;
break; missing. Otherwise static analyzers will complain.
> + default:
> + break;
> + }
Same as above (and, in this case, prove in point why break;
should always be added even if it seems unnecessary).
> + case hwmon_pwm:
> + switch (attr) {
> + case hwmon_pwm_input:
> + mode = 0644;
Same as above.
> + default:
> + break;
> + }
Same as above.
> + default:
> + break;
> + }
> +
> + return mode;
> +}
> +
> +static const struct hwmon_ops gxp_fan_ctrl_ops = {
> + .is_visible = gxp_fan_ctrl_is_visible,
> + .read = gxp_fan_ctrl_read,
> + .write = gxp_fan_ctrl_write,
> +};
> +
> +static const struct hwmon_channel_info *gxp_fan_ctrl_info[] = {
> + HWMON_CHANNEL_INFO(fan,
> + HWMON_F_FAULT | HWMON_F_ENABLE,
> + HWMON_F_FAULT | HWMON_F_ENABLE,
> + HWMON_F_FAULT | HWMON_F_ENABLE,
> + HWMON_F_FAULT | HWMON_F_ENABLE,
> + HWMON_F_FAULT | HWMON_F_ENABLE,
> + HWMON_F_FAULT | HWMON_F_ENABLE,
> + HWMON_F_FAULT | HWMON_F_ENABLE,
> + HWMON_F_FAULT | HWMON_F_ENABLE),
> + HWMON_CHANNEL_INFO(pwm,
> + HWMON_PWM_INPUT | HWMON_PWM_ENABLE,
> + HWMON_PWM_INPUT | HWMON_PWM_ENABLE,
> + HWMON_PWM_INPUT | HWMON_PWM_ENABLE,
> + HWMON_PWM_INPUT | HWMON_PWM_ENABLE,
> + HWMON_PWM_INPUT | HWMON_PWM_ENABLE,
> + HWMON_PWM_INPUT | HWMON_PWM_ENABLE,
> + HWMON_PWM_INPUT | HWMON_PWM_ENABLE,
> + HWMON_PWM_INPUT | HWMON_PWM_ENABLE),
> + NULL
> +};
> +
> +static const struct hwmon_chip_info gxp_fan_ctrl_chip_info = {
> + .ops = &gxp_fan_ctrl_ops,
> + .info = gxp_fan_ctrl_info,
> +
> +};
> +
> +static struct regmap *gxp_fan_ctrl_init_regmap(struct platform_device *pdev, char *reg_name)
> +{
> + struct regmap_config regmap_config = {
> + .reg_bits = 32,
> + .reg_stride = 4,
> + .val_bits = 32,
> + };
> + void __iomem *base;
> +
> + base = devm_platform_ioremap_resource_byname(pdev, reg_name);
> + if (IS_ERR(base))
> + return ERR_CAST(base);
> +
> + regmap_config.name = reg_name;
> +
> + return devm_regmap_init_mmio(&pdev->dev, base, ®map_config);
> +}
> +
> +static int gxp_fan_ctrl_probe(struct platform_device *pdev)
> +{
> + struct gxp_fan_ctrl_drvdata *drvdata;
> + struct resource *res;
> + struct device *dev = &pdev->dev;
> + int error;
> +
> + drvdata = devm_kzalloc(&pdev->dev, sizeof(struct gxp_fan_ctrl_drvdata),
> + GFP_KERNEL);
There is a local variable (dev) pointing to &pdev->dev.
I would suggest to use it.
> + if (!drvdata)
> + return -ENOMEM;
> +
> + drvdata->dev = &pdev->dev;
> +
> + platform_set_drvdata(pdev, drvdata);
There is no platform_get_drvdata() in this code, meaning
platform_set_drvdata() is unnecessary.
> +
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + drvdata->base = devm_ioremap_resource(&pdev->dev, res);
> + if (IS_ERR(drvdata->base)) {
> + error = dev_err_probe(dev, PTR_ERR(drvdata->base),
> + "failed to map base\n");
> + goto free_mem;
> + }
> + drvdata->plreg_map = gxp_fan_ctrl_init_regmap(pdev, "pl");
> + if (IS_ERR(drvdata->plreg_map)) {
> + error = dev_err_probe(dev, PTR_ERR(drvdata->plreg_map),
> + "failed to map plreg_handle\n");
> + goto free_mem;
> + }
> +
> + drvdata->fn2_map = gxp_fan_ctrl_init_regmap(pdev, "fn2");
> + if (IS_ERR(drvdata->fn2_map)) {
> + error = dev_err_probe(dev, PTR_ERR(drvdata->fn2_map),
> + "failed to map fn2_handle\n");
> + goto free_mem;
> + }
> +
> + drvdata->hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev,
> + "fan_ctrl",
fan_ctrl is a bit generic. Normally this reflects the driver name.
> + drvdata,
> + &gxp_fan_ctrl_chip_info,
> + NULL);
> +
> + if (IS_ERR(drvdata->hwmon_dev)) {
> + error = dev_err_probe(dev, PTR_ERR(drvdata->hwmon_dev),
> + "failed to register fan ctrl\n");
> +
> + goto free_mem;
> + }
> +
> + return 0;
> +
> +free_mem:
> + kfree(drvdata);
drvdata was allocated with a devm function. Releasing it with kfree
results in a double free. This goto and error handling is not only
unnecessary but wrong.
> + return error;
> +}
> +
> +static const struct of_device_id gxp_fan_ctrl_of_match[] = {
> + { .compatible = "hpe,gxp-fan-ctrl", },
> + {},
> +};
> +MODULE_DEVICE_TABLE(of, gxp_fan_ctrl_of_match);
> +
> +static struct platform_driver gxp_fan_ctrl_driver = {
> + .probe = gxp_fan_ctrl_probe,
> + .driver = {
> + .name = "gxp-fan-ctrl",
> + .of_match_table = gxp_fan_ctrl_of_match,
> + },
> +};
> +module_platform_driver(gxp_fan_ctrl_driver);
> +
> +MODULE_AUTHOR("Nick Hawkins <nick.hawkins@xxxxxxx>");
> +MODULE_DESCRIPTION("HPE GXP fan controller");
> +MODULE_LICENSE("GPL");