Re: [PATCH 2/2] cpufreq: ti: Add cpufreq driver to determine available OPPs at runtime

[Viresh Kumar]

On 18-05-16, 18:30, Dave Gerlach wrote:
> Some TI SoCs, like those in the AM335x, AM437x, DRA7x, and AM57x families,
> have different OPPs available for the MPU depending on which specific
> variant of the SoC is in use. This can be determined through use of the
> revision and an eFuse register present in the silicon. Introduce a
> ti-cpufreq driver that can read the aformentioned values and provide
> them as version matching data to the opp framework. Through this the
> opp-supported-hw dt binding that is part of the operating-points-v2
> table can be used to indicate availability of OPPs for each device.
> 
> This driver also creates the "cpufreq-dt" platform_device after passing
> the version matching data to the OPP framework so that the cpufreq-dt
> handles the actual cpufreq implementation. Even without the necessary
> data to pass the version matching data the driver will still create this
> device to maintain backwards compatibility with operating-points v1
> tables.
> 
> Signed-off-by: Dave Gerlach <d-gerlach@xxxxxx>
> ---
>  drivers/cpufreq/Kconfig.arm  |  11 ++
>  drivers/cpufreq/Makefile     |   1 +
>  drivers/cpufreq/ti-cpufreq.c | 254 +++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 266 insertions(+)
>  create mode 100644 drivers/cpufreq/ti-cpufreq.c
> 
> diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
> index d89b8afe23b6..0dea6849ac3e 100644
> --- a/drivers/cpufreq/Kconfig.arm
> +++ b/drivers/cpufreq/Kconfig.arm
> @@ -234,6 +234,17 @@ config ARM_TEGRA124_CPUFREQ
>  	help
>  	  This adds the CPUFreq driver support for Tegra124 SOCs.
>  
> +config ARM_TI_CPUFREQ
> +	tristate "Texas Instruments CPUFreq support"

You sure you want to get it compiled as a module? And don't provide
module_exit() at all?

> +	depends on ARCH_OMAP2PLUS
> +	help
> +	  This driver enables valid OPPs on the running platform based on
> +	  values contained within the SoC in use. Enable this in order to
> +	  use the cpufreq-dt driver on all Texas Instruments platforms that
> +	  provide dt based operating-points-v2 tables with opp-supported-hw
> +	  data provided. Required for cpufreq support on AM335x, AM437x,
> +	  DRA7x, and AM57x platforms.
> +
>  config ARM_PXA2xx_CPUFREQ
>  	tristate "Intel PXA2xx CPUfreq driver"
>  	depends on PXA27x || PXA25x
> diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
> index 0a9b6a093646..5b1b6ec0a9f0 100644
> --- a/drivers/cpufreq/Makefile
> +++ b/drivers/cpufreq/Makefile
> @@ -77,6 +77,7 @@ obj-$(CONFIG_ARM_SPEAR_CPUFREQ)		+= spear-cpufreq.o
>  obj-$(CONFIG_ARM_STI_CPUFREQ)		+= sti-cpufreq.o
>  obj-$(CONFIG_ARM_TEGRA20_CPUFREQ)	+= tegra20-cpufreq.o
>  obj-$(CONFIG_ARM_TEGRA124_CPUFREQ)	+= tegra124-cpufreq.o
> +obj-$(CONFIG_ARM_TI_CPUFREQ)		+= ti-cpufreq.o
>  obj-$(CONFIG_ARM_VEXPRESS_SPC_CPUFREQ)	+= vexpress-spc-cpufreq.o
>  obj-$(CONFIG_ACPI_CPPC_CPUFREQ) += cppc_cpufreq.o
>  obj-$(CONFIG_MACH_MVEBU_V7)		+= mvebu-cpufreq.o
> diff --git a/drivers/cpufreq/ti-cpufreq.c b/drivers/cpufreq/ti-cpufreq.c
> new file mode 100644
> index 000000000000..e47b452aadd0
> --- /dev/null
> +++ b/drivers/cpufreq/ti-cpufreq.c
> @@ -0,0 +1,254 @@
> +/*
> + * TI CPUFreq/OPP hw-supported driver
> + *
> + * Copyright (C) 2016 Texas Instruments, Inc.
> + *	 Dave Gerlach <d-gerlach@xxxxxx>
> + *
> + * 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.
> + *
> + * 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/cpu.h>
> +#include <linux/io.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_platform.h>
> +#include <linux/pm_opp.h>
> +#include <linux/regmap.h>
> +
> +#define REVISION_MASK				(0xF << 28)

Use below shift-mask here ?

> +#define REVISION_SHIFT				28
> +
> +#define DRA7_EFUSE_HAS_OD_MPU_OPP		11
> +#define DRA7_EFUSE_HAS_HIGH_MPU_OPP		15
> +#define DRA7_EFUSE_HAS_ALL_MPU_OPP		23
> +
> +#define DRA7_EFUSE_NOM_MPU_OPP			BIT(0)
> +#define DRA7_EFUSE_OD_MPU_OPP			BIT(1)
> +#define DRA7_EFUSE_HIGH_MPU_OPP			BIT(2)
> +
> +#define VERSION_COUNT				2
> +
> +static struct ti_cpufreq_data {
> +	struct device *cpu;
> +	struct regmap *opp_efuse;
> +	struct regmap *revision;
> +} opp_data;
> +
> +static struct ti_cpufreq_soc_data {
> +	unsigned long (*efuse_xlate)(unsigned long efuse);
> +} *soc_data;
> +
> +static unsigned long amx3_efuse_xlate(unsigned long efuse)
> +{
> +	/* AM335x and AM437x use "OPP disable" bits, so invert */
> +	return ~efuse;
> +}
> +
> +static unsigned long dra7_efuse_xlate(unsigned long efuse)
> +{
> +	unsigned long calculated_efuse = DRA7_EFUSE_NOM_MPU_OPP;
> +
> +	/*
> +	 * The efuse on dra7 and am57 parts contains a specific
> +	 * value indicating the highest available OPP.
> +	 */
> +
> +	switch (efuse) {
> +	case DRA7_EFUSE_HAS_ALL_MPU_OPP:
> +	case DRA7_EFUSE_HAS_HIGH_MPU_OPP:
> +		calculated_efuse |= DRA7_EFUSE_HIGH_MPU_OPP;
> +	case DRA7_EFUSE_HAS_OD_MPU_OPP:
> +		calculated_efuse |= DRA7_EFUSE_OD_MPU_OPP;
> +	}
> +
> +	return calculated_efuse;
> +}
> +
> +static struct ti_cpufreq_soc_data amx3_soc_data = {
> +	.efuse_xlate = amx3_efuse_xlate,
> +};
> +
> +static struct ti_cpufreq_soc_data dra7_soc_data = {
> +	.efuse_xlate = dra7_efuse_xlate,
> +};
> +
> +/**
> + * ti_cpufreq_get_efuse() - Parse and return efuse value present on SoC
> + * @efuse_value: Set to the value parsed from efuse
> + *
> + * Returns error code if efuse not read properly.
> + */
> +static int ti_cpufreq_get_efuse(u32 *efuse_value)
> +{
> +	struct device *dev = opp_data.cpu;
> +	struct device_node *np = dev->of_node;
> +	unsigned int efuse_offset;
> +	u32 efuse, efuse_mask, efuse_shift;
> +	int ret;
> +
> +	ret = of_property_read_u32_index(np, "ti,syscon-efuse",
> +					 1, &efuse_offset);
> +	if (ret) {
> +		dev_err(dev,

Line break here isn't required.

> +			"No efuse offset provided %s: %d\n",
> +			np->full_name, ret);
> +		return ret;
> +	}
> +
> +	ret = of_property_read_u32_index(np, "ti,syscon-efuse", 2,
> +					 &efuse_mask);
> +	if (ret)
> +		efuse_mask = 0xffffffff;
> +
> +	ret = of_property_read_u32_index(np, "ti,syscon-efuse", 3,
> +					 &efuse_shift);
> +	if (ret)
> +		efuse_shift = 0;

Why don't you read an array of 3 integers in one go?

> +
> +	ret = regmap_read(opp_data.opp_efuse, efuse_offset, &efuse);
> +	if (ret) {
> +		dev_err(dev,
> +			"Failed to read the efuse value from syscon: %d\n",
> +			ret);
> +		return ret;
> +	}
> +
> +	efuse = (efuse & efuse_mask) >> efuse_shift;
> +
> +	*efuse_value = soc_data->efuse_xlate(efuse);
> +
> +	return 0;
> +}
> +
> +/**
> + * ti_cpufreq_get_rev() - Parse and return rev value present on SoC
> + * @revision_value: Set to the value parsed from revision register
> + *
> + * Returns error code if revision not read properly.
> + */
> +static int ti_cpufreq_get_rev(u32 *revision_value)
> +{
> +	struct device *dev = opp_data.cpu;
> +	struct device_node *np = dev->of_node;
> +	unsigned int revision_offset;
> +	u32 revision;
> +	int ret;
> +
> +	ret = of_property_read_u32_index(np, "ti,syscon-rev",
> +					 1, &revision_offset);
> +	if (ret) {
> +		dev_err(dev,
> +			"No revision offset provided %s [%d]\n",
> +			np->full_name, ret);
> +		return ret;
> +	}
> +
> +	ret = regmap_read(opp_data.revision, revision_offset, &revision);
> +	if (ret) {
> +		dev_err(dev,
> +			"Failed to read the revision number from syscon: %d\n",
> +			ret);
> +		return ret;
> +	}
> +
> +	*revision_value = BIT((revision & REVISION_MASK) >> REVISION_SHIFT);

That's an crazy operation.

So you first shifted 0xF << 27, and then right shifted everything by 27 bits :)

You should rather do:

#define REVISION_MASK   0xF
(revision >> REVISION_SHIFT) & REVISION_MASK

> +
> +	return 0;
> +}
> +
> +static int ti_cpufreq_setup_syscon_registers(void)
> +{
> +	struct device *dev = opp_data.cpu;
> +	struct device_node *np = dev->of_node;
> +
> +	opp_data.opp_efuse = syscon_regmap_lookup_by_phandle(np,
> +							"ti,syscon-efuse");
> +	if (IS_ERR(opp_data.opp_efuse)) {
> +		dev_dbg(dev,  "\"ti,syscon-efuse\" is missing, cannot use OPPv2 table.\n");
> +		return PTR_ERR(opp_data.opp_efuse);
> +	}
> +
> +	opp_data.revision = syscon_regmap_lookup_by_phandle(np,
> +							"ti,syscon-rev");
> +	if (IS_ERR(opp_data.revision)) {
> +		dev_dbg(dev,  "\"ti,syscon-rev\" is missing, cannot use OPPv2 table.\n");

These messages are wrong as your code is going to use opp-v2 anyway.

> +		return PTR_ERR(opp_data.revision);
> +	}
> +
> +	return 0;
> +}
> +
> +static struct ti_cpufreq_soc_data *ti_cpufreq_get_soc_data(void)
> +{
> +	if (of_machine_is_compatible("ti,am33xx") ||
> +	    of_machine_is_compatible("ti,am4372"))
> +		return &amx3_soc_data;
> +	else if (of_machine_is_compatible("ti,dra7"))
> +		return &dra7_soc_data;
> +	else
> +		return NULL;
> +}
> +
> +static int ti_cpufreq_init(void)

__init ?

> +{
> +	int ret;
> +	u32 version[VERSION_COUNT];
> +
> +	soc_data = ti_cpufreq_get_soc_data();
> +	if (!soc_data)
> +		return -ENODEV;

Why not use of_match_node() and an array of type struct of_device_id instead of
above function?

> +
> +	opp_data.cpu = get_cpu_device(0);
> +	if (!opp_data.cpu) {
> +		pr_err("%s: Failed to get device for CPU0\n", __func__);
> +		return -ENODEV;
> +	}
> +
> +	if (!of_get_property(opp_data.cpu->of_node, "operating-points-v2",
> +			     NULL)) {
> +		dev_info(opp_data.cpu, "OPP-v2 not supported, cpufreq-dt will attempt to use legacy tables.\n");
> +		goto register_cpufreq_dt;
> +	}
> +
> +	ret = ti_cpufreq_setup_syscon_registers();
> +	if (ret)
> +		goto register_cpufreq_dt;
> +
> +	/*
> +	 * OPPs determine whether or not they are supported based on
> +	 * two metrics:
> +	 *	0 - SoC Revision
> +	 *	1 - eFuse value
> +	 */
> +	ret = ti_cpufreq_get_rev(&version[0]);
> +	if (ret)
> +		return ret;
> +
> +	ret = ti_cpufreq_get_efuse(&version[1]);
> +	if (ret)
> +		return ret;
> +
> +	ret = dev_pm_opp_set_supported_hw(opp_data.cpu, version, VERSION_COUNT);
> +	if (ret) {
> +		dev_err(opp_data.cpu, "Failed to set supported hardware\n");
> +		return ret;
> +	}
> +
> +register_cpufreq_dt:
> +	platform_device_register_simple("cpufreq-dt", -1, NULL, 0);
> +
> +	return 0;
> +}
> +module_init(ti_cpufreq_init);
> +
> +MODULE_DESCRIPTION("TI CPUFreq/OPP hw-supported driver");
> +MODULE_AUTHOR("Dave Gerlach <d-gerlach@xxxxxx>");
> +MODULE_LICENSE("GPL v2");
> -- 
> 2.7.3

-- 
viresh