On 12/13/19 10:30 AM, Chanwoo Choi wrote:
> Hi,
>
> On 11/15/19 5:09 AM, Leonard Crestez wrote:
>> Add initial support for dynamic frequency switching on pieces of the imx
>> interconnect fabric.
>>
>> All this driver does is set a clk rate based on an opp table, it does
>> not map register areas.
>>
>> Signed-off-by: Leonard Crestez <leonard.crestez@xxxxxxx>
>> ---
>> drivers/devfreq/Kconfig | 9 ++
>> drivers/devfreq/Makefile | 1 +
>> drivers/devfreq/imx-devfreq.c | 150 ++++++++++++++++++++++++++++++++++
>> 3 files changed, 160 insertions(+)
>> create mode 100644 drivers/devfreq/imx-devfreq.c
>>
>> diff --git a/drivers/devfreq/Kconfig b/drivers/devfreq/Kconfig
>> index 923a6132e741..fef5ce831e90 100644
>> --- a/drivers/devfreq/Kconfig
>> +++ b/drivers/devfreq/Kconfig
>> @@ -98,10 +98,19 @@ config ARM_IMX8M_DDRC_DEVFREQ
>> select DEVFREQ_GOV_USERSPACE
>> help
>> This adds the DEVFREQ driver for the i.MX8M DDR Controller. It allows
>> adjusting DRAM frequency.
>>
>> +config ARM_IMX_DEVFREQ
>> + tristate "i.MX Generic DEVFREQ Driver"
>> + depends on ARCH_MXC || COMPILE_TEST
>> + select DEVFREQ_GOV_PASSIVE
>> + select DEVFREQ_GOV_USERSPACE
>> + help
>> + This adds the generic DEVFREQ driver for i.MX interconnects. It
>> + allows adjusting NIC/NOC frequency.
>> +
>> config ARM_TEGRA_DEVFREQ
>> tristate "NVIDIA Tegra30/114/124/210 DEVFREQ Driver"
>> depends on ARCH_TEGRA_3x_SOC || ARCH_TEGRA_114_SOC || \
>> ARCH_TEGRA_132_SOC || ARCH_TEGRA_124_SOC || \
>> ARCH_TEGRA_210_SOC || \
>> diff --git a/drivers/devfreq/Makefile b/drivers/devfreq/Makefile
>> index 3eb4d5e6635c..61d0edee16f7 100644
>> --- a/drivers/devfreq/Makefile
>> +++ b/drivers/devfreq/Makefile
>> @@ -8,10 +8,11 @@ obj-$(CONFIG_DEVFREQ_GOV_USERSPACE) += governor_userspace.o
>> obj-$(CONFIG_DEVFREQ_GOV_PASSIVE) += governor_passive.o
>>
>> # DEVFREQ Drivers
>> obj-$(CONFIG_ARM_EXYNOS_BUS_DEVFREQ) += exynos-bus.o
>> obj-$(CONFIG_ARM_IMX8M_DDRC_DEVFREQ) += imx8m-ddrc.o
>> +obj-$(CONFIG_ARM_IMX_DEVFREQ) += imx-devfreq.o
>> obj-$(CONFIG_ARM_RK3399_DMC_DEVFREQ) += rk3399_dmc.o
>> obj-$(CONFIG_ARM_TEGRA_DEVFREQ) += tegra30-devfreq.o
>> obj-$(CONFIG_ARM_TEGRA20_DEVFREQ) += tegra20-devfreq.o
>>
>> # DEVFREQ Event Drivers
>> diff --git a/drivers/devfreq/imx-devfreq.c b/drivers/devfreq/imx-devfreq.c
>> new file mode 100644
>> index 000000000000..620b344e87aa
>> --- /dev/null
>> +++ b/drivers/devfreq/imx-devfreq.c
>> @@ -0,0 +1,150 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Copyright 2019 NXP
>> + */
>> +
>> +#include <linux/clk.h>
>> +#include <linux/devfreq.h>
>> +#include <linux/device.h>
>> +#include <linux/module.h>
>> +#include <linux/of_device.h>
>> +#include <linux/pm_opp.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/slab.h>
>> +
>> +struct imx_devfreq {
>> + struct devfreq_dev_profile profile;
>> + struct devfreq *devfreq;
>> + struct clk *clk;
>> + struct devfreq_passive_data passive_data;
>> +};
>> +
>> +static int imx_devfreq_target(struct device *dev,
>> + unsigned long *freq, u32 flags)
>
> Don't use space for the indentation. Please use only tab.
>
>> +{
>> + struct imx_devfreq *priv = dev_get_drvdata(dev);
>> + struct dev_pm_opp *new_opp;
>> + unsigned long new_freq;
>> + int ret;
>> +
>> + new_opp = devfreq_recommended_opp(dev, freq, flags);
>> + if (IS_ERR(new_opp)) {
>> + ret = PTR_ERR(new_opp);
>> + dev_err(dev, "failed to get recommended opp: %d\n", ret);
>> + return ret;
>> + }
>> + new_freq = dev_pm_opp_get_freq(new_opp);
>> + dev_pm_opp_put(new_opp);
>> +
>> + return clk_set_rate(priv->clk, new_freq);
>> +}
>> +
>> +static int imx_devfreq_get_cur_freq(struct device *dev, unsigned long *freq)
>> +{
>> + struct imx_devfreq *priv = dev_get_drvdata(dev);
>> +
>> + *freq = clk_get_rate(priv->clk);
>> +
>> + return 0;
>> +}
>> +
>> +static int imx_devfreq_get_dev_status(struct device *dev,
>> + struct devfreq_dev_status *stat)
>
> ditto. Please use tab for the indentation.
>
>> +{
>> + struct imx_devfreq *priv = dev_get_drvdata(dev);
>> +
>> + stat->busy_time = 0;
>> + stat->total_time = 0;
>> + stat->current_frequency = clk_get_rate(priv->clk);
>> +
>> + return 0;
>> +}
>> +
>> +static void imx_devfreq_exit(struct device *dev)
>> +{
>> + dev_pm_opp_of_remove_table(dev);
>> +}
>> +
>> +static int imx_devfreq_probe(struct platform_device *pdev)
>> +{
>> + struct device *dev = &pdev->dev;
>> + struct imx_devfreq *priv;
>
> How about changing the variable name 'priv' to 'imx' or 'imx_data'?
> because it is not easy to catch the role of 'priv' from variable name.
>
>> + const char *gov = DEVFREQ_GOV_USERSPACE;
>> + void *govdata = NULL;
>
> How about changing the variable name 'govdata' to 'gov_data'?
> - govdata -> gov_data
>
>> + int ret;
>> +
>> + priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
>> + if (!priv)
>> + return -ENOMEM;
>> +
>> + priv->clk = devm_clk_get(dev, NULL);
>
> nitpick: because the clock-name is not mandatory.
> Don't need to specify the clock name to inform the role of clock
> of other developer/user?
>
> For example, "ddr", "bus" and so on.
And, this driver doesn't include the 'clk_prepare_enable'.
how to enable the clock?
>
>> + if (IS_ERR(priv->clk)) {
>> + ret = PTR_ERR(priv->clk);
>> + dev_err(dev, "failed to fetch clk: %d\n", ret);
>> + return ret;
>> + }
>> + platform_set_drvdata(pdev, priv);
>> +
>> + ret = dev_pm_opp_of_add_table(dev);
>> + if (ret < 0) {
>> + dev_err(dev, "failed to get OPP table\n");
>> + return ret;
>> + }
>> +
>> + priv->profile.polling_ms = 1000;
>> + priv->profile.target = imx_devfreq_target;
>> + priv->profile.get_dev_status = imx_devfreq_get_dev_status;
>> + priv->profile.exit = imx_devfreq_exit;
>> + priv->profile.get_cur_freq = imx_devfreq_get_cur_freq;
>> + priv->profile.initial_freq = clk_get_rate(priv->clk);
>> +
>> + /* Handle passive devfreq parent link */
>> + priv->passive_data.parent = devfreq_get_devfreq_by_phandle(dev, 0);
>> + if (!IS_ERR(priv->passive_data.parent)) {
>> + dev_info(dev, "setup passive link to %s\n",
>> + dev_name(priv->passive_data.parent->dev.parent));
>> + gov = DEVFREQ_GOV_PASSIVE;
>> + govdata = &priv->passive_data;
>> + } else if (priv->passive_data.parent != ERR_PTR(-ENODEV)) {
>> + // -ENODEV means no parent: not an error.
>> + ret = PTR_ERR(priv->passive_data.parent);
>> + if (ret != -EPROBE_DEFER)
>> + dev_warn(dev, "failed to get initialize passive parent: %d\n",
>> + ret);
>> + goto err;
>> + }
>
> You better to change the exception handling as following: It is more simple.
>
> } else if (PTR_ERR(priv->passive_data.parent) == -EPROBE_DEFER)
> || PTR_ERR(priv->passive_data.parent) == -ENODEV) {
> goto err;
> } else {
> ret = PTR_ERR(priv->passive_data.parent);
> dev_err(dev, "failed to get initialize passive parent: %d\n", ret);
> goto err;
> }
>
>> +
>> + priv->devfreq = devm_devfreq_add_device(dev, &priv->profile,
>> + gov, govdata);
>> + if (IS_ERR(priv->devfreq)) {
>> + ret = PTR_ERR(priv->devfreq);
>> + dev_err(dev, "failed to add devfreq device: %d\n", ret);
>> + goto err;
>> + }
>> +
>> + return 0;
>> +
>> +err:
>> + dev_pm_opp_of_remove_table(dev);
>> + return ret;
>> +}
>> +
>> +static const struct of_device_id imx_devfreq_of_match[] = {
>> + { .compatible = "fsl,imx8m-noc", },
>> + { .compatible = "fsl,imx8m-nic", },
>> + { /* sentinel */ },
>> +};
>> +MODULE_DEVICE_TABLE(of, imx_devfreq_of_match);
>> +
>> +static struct platform_driver imx_devfreq_platdrv = {
>> + .probe = imx_devfreq_probe,
>> + .driver = {
>> + .name = "imx-devfreq",
>> + .of_match_table = of_match_ptr(imx_devfreq_of_match),
>> + },
>> +};
>> +module_platform_driver(imx_devfreq_platdrv);
>> +
>> +MODULE_DESCRIPTION("Generic i.MX bus frequency driver");
>
> If this driver is for bus frequency, you better to use 'bus' for the clock-name
> for the readability.
>
>> +MODULE_AUTHOR("Leonard Crestez <leonard.crestez@xxxxxxx>");
>> +MODULE_LICENSE("GPL v2");
>>
>
>
--
Best Regards,
Chanwoo Choi
Samsung Electronics
