Re: [PATCH v2] PM / AVS: rockchip-io: add driver handling Rockchip io domains

[Doug Anderson]

Santosh,

On Thu, Sep 11, 2014 at 2:31 PM, Santosh Shilimkar
<santosh.shilimkar@xxxxxx> wrote:
>> +Required properties:
>> +- compatible: should be one of:
>> +  - "rockchip,rk3188-iodomain" for rk3188
>> +  - "rockchip,rk3288-iodomain" for rk3288
> The key word 'voltage' is missing from the compatible. iodomain itself
> doesn't convey what it is actually.

Sure, so you want "rockchip,rk3288-io-voltage-domain" then?


>> +- rockchip,grf: phandle to the syscon managing the "general register files"
>> +
>> +
>> +You specify supplies using the standard regulator bindings by including
>> +a phandle the the relevant regulator.  All specified supplies must be able
>> +to report their voltage.  The IO Voltage Domain for any non-specified
>> +supplies will be not be touched.
>> +
>> +Possible supplies for rk3188:
>> +- ap0-supply:    The supply connected to AP0_VCC.
>> +- ap1-supply:    The supply connected to AP1_VCC.
>> +- cif-supply:    The supply connected to CIF_VCC.
>> +- flash-supply:  The supply connected to FLASH_VCC.
>> +- lcdc0-supply:  The supply connected to LCD0_VCC.
>> +- lcdc1-supply:  The supply connected to LCD1_VCC.
>> +- vccio0-supply: The supply connected to VCCIO0.
>> +- vccio1-supply: The supply connected to VCCIO1.
>> +                 Sometimes also labeled VCCIO1 and VCCIO2.
>> +
>> +Possible supplies for rk3288:
>> +- audio-supply:  The supply connected to APIO4_VDD.
>> +- bb-supply:     The supply connected to APIO5_VDD.
>> +- dvp-supply:    The supply connected to DVPIO_VDD.
>> +- flash0-supply: The supply connected to FLASH0_VDD.  Typically for eMMC
>> +- flash1-supply: The supply connected to FLASH1_VDD.  Also known as SDIO1.
>> +- gpio30-supply: The supply connected to APIO1_VDD.
>> +- gpio1830       The supply connected to APIO2_VDD.
>> +- lcdc-supply:   The supply connected to LCDC_VDD.
>> +- sdcard-supply: The supply connected to SDMMC0_VDD.
>> +- wifi-supply:   The supply connected to APIO3_VDD.  Also known as SDIO0.
>> +
>> +
>> +Example:
>> +
>> +     io-domains {
>> +             compatible = "rockchip,rk3288-iodomain";
>> +             rockchip,grf = <&grf>;
>> +
>> +             audio-supply = <&vcc18_codec>;
>> +             bb-supply = <&vcc33_io>;
>> +             dvp-supply = <&vcc_18>;
>> +             flash0-supply = <&vcc18_flashio>;
>> +             gpio1830-supply = <&vcc33_io>;
>> +             gpio30-supply = <&vcc33_pmuio>;
>> +             lcdc-supply = <&vcc33_lcd>;
>> +             sdcard-supply = <&vccio_sd>;
>> +             wifi-supply = <&vcc18_wl>;
>> +     };
>> diff --git a/drivers/power/avs/Kconfig b/drivers/power/avs/Kconfig
>> index 2a1008b..7f3d389 100644
>> --- a/drivers/power/avs/Kconfig
>> +++ b/drivers/power/avs/Kconfig
>> @@ -10,3 +10,11 @@ menuconfig POWER_AVS
>>         AVS is also called SmartReflex on OMAP devices.
>>
>>         Say Y here to enable Adaptive Voltage Scaling class support.
>> +
>> +config ROCKCHIP_IODOMAIN
>> +        tristate "Rockchip IO domain support"
>> +        depends on ARCH_ROCKCHIP && OF
>> +        help
>> +          Say y here to enable support io domains on Rockchip SoCs. It is
>> +          necessary for the io domain setting of the SoC to match the
>> +          voltage supplied by the regulators.
>> diff --git a/drivers/power/avs/Makefile b/drivers/power/avs/Makefile
>> index 0843386..ba4c7bc 100644
>> --- a/drivers/power/avs/Makefile
>> +++ b/drivers/power/avs/Makefile
>> @@ -1 +1,2 @@
>>  obj-$(CONFIG_POWER_AVS_OMAP)         += smartreflex.o
>> +obj-$(CONFIG_ROCKCHIP_IODOMAIN)              += rockchip-io-domain.o
>> diff --git a/drivers/power/avs/rockchip-io-domain.c b/drivers/power/avs/rockchip-io-domain.c
>> new file mode 100644
>> index 0000000..f4e0ebc
>> --- /dev/null
>> +++ b/drivers/power/avs/rockchip-io-domain.c
>> @@ -0,0 +1,333 @@
>> +/*
>> + * Rockchip IO Voltage Domain driver
>> + *
>> + * Copyright 2014 MundoReader S.L.
>> + * Copyright 2014 Google, Inc.
>> + *
>> + * This software is licensed under the terms of the GNU General Public
>> + * License version 2, as published by the Free Software Foundation, and
>> + * may be copied, distributed, and modified under those terms.
>> + *
>> + * 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/kernel.h>
>> +#include <linux/module.h>
>> +#include <linux/err.h>
>> +#include <linux/mfd/syscon.h>
> The bindings are not talking about syscon usage. You might
> want to document it appropriately to make the usage clear.

Doesn't the bindings have this?

> +- rockchip,grf: phandle to the syscon managing the "general register files"

I actually forgot that in v1, but I added it to v2.


>> +#define MAX_VOLTAGE_1_8              1980000
> This is close to 2V, Is that intentional.
>
>> +#define MAX_VOLTAGE_3_3              3600000
>> +
> Same here.

I got these numbers from the document "Rocchip RK3288 datasheet".
Under "Recommended Operating Conditions" for "Digital GPIO".  When the
typical is 3.3V the max is 3.6V.  When the typical is 1.8V the max is
1.98V.

The way these numbers are used is:

If the voltage on a rail is above the "1.8" voltage (1.98V) we'll tell
the SoC we're at 3.3.  If the voltage on a rail is above the "3.3V"
we'll consider that to be an error.

There's one secret ulterior motive here though that I'll admit to.
When a client uses regulator_set_voltage() they actually specify a min
and max voltage.  They might say that they want 3.3V by saying that
they want a voltage between 2.7V and 3.6V.  They might say that they
want 1.8V by saying that they want a voltage between 1.7V and 1.95V.
In our pre-change notification we are only told the possible range.
It's nice if things work properly in that case.  If we find some case
that doesn't work later we can always get fancier and try to figure
out what voltage the regulator will end up at, but I haven't seen the
need yet.

Note that the 1.7 - 1.95V is more than hypothetical.  dw_mmc requests
those ranges.  I'll admit that I was involved in that code, but I'll
also admit to having stolen those numbers from sdhci.


>> +struct rockchip_iodomain;
>> +
>> +/**
>> + * @supplies: voltage settings matching the register bits.
>> + */
>> +struct rockchip_iodomain_soc_data {
>> +     int grf_offset;
>> +     const char *supply_names[MAX_SUPPLIES];
>> +     void (*init)(struct rockchip_iodomain *iod);
>> +};
>> +
>> +struct rockchip_iodomain_supply {
>> +     struct rockchip_iodomain *iod;
>> +     struct regulator *reg;
>> +     struct notifier_block nb;
>> +     int idx;
>> +};
>> +
>> +struct rockchip_iodomain {
>> +     struct device *dev;
>> +     struct regmap *grf;
>> +     struct rockchip_iodomain_soc_data *soc_data;
>> +     struct rockchip_iodomain_supply supplies[MAX_SUPPLIES];
>> +};
>> +
>> +static int rockchip_iodomain_write(struct rockchip_iodomain_supply *supply,
>> +                                int uV)
>> +{
>> +     struct rockchip_iodomain *iod = supply->iod;
>> +     u32 val;
>> +     int ret;
>> +
>> +     /* set value bit */
>> +     val = (uV > MAX_VOLTAGE_1_8) ? 0 : 1;
>> +     val <<= supply->idx;
>> +
>> +     /* apply hiword-mask */
>> +     val |= (BIT(supply->idx) << 16);
>> +
>> +     ret = regmap_write(iod->grf, iod->soc_data->grf_offset, val);
>> +     if (ret)
>> +             dev_err(iod->dev, "Couldn't write to GRF\n");
>> +
>> +     return ret;
>> +}
>> +
>> +static int rockchip_iodomain_notify(struct notifier_block *nb,
>> +                                 unsigned long event,
>> +                                 void *data)
>> +{
>> +     struct rockchip_iodomain_supply *supply =
>> +                     container_of(nb, struct rockchip_iodomain_supply, nb);
>> +     int uV;
>> +     int ret;
>> +
>> +     /*
>> +      * According to Rockchip it's important to keep the SoC IO domain
>> +      * higher than (or equal to) the external voltage.  That means we need
>> +      * to change it before external voltage changes happen in the case
>> +      * of an increase.
>> +      */
>> +     if (event & REGULATOR_EVENT_PRE_VOLTAGE_CHANGE) {
>> +             struct pre_voltage_change_data *pvc_data = data;
>> +
>> +             uV = max_t(unsigned long, pvc_data->old_uV, pvc_data->max_uV);
>> +     } else if (event & (REGULATOR_EVENT_VOLTAGE_CHANGE |
>> +                         REGULATOR_EVENT_ABORT_VOLTAGE_CHANGE)) {
>> +             uV = (unsigned long)data;
>> +     } else {
>> +             return NOTIFY_OK;
>> +     }
>> +
>> +     dev_dbg(supply->iod->dev, "Setting to %d\n", uV);
>> +
>> +     if (uV > MAX_VOLTAGE_3_3) {
>> +             dev_err(supply->iod->dev, "Voltage too high: %d\n", uV);
>> +
>> +             if (event == REGULATOR_EVENT_PRE_VOLTAGE_CHANGE)
>> +                     return NOTIFY_BAD;
>> +     }
>> +
>> +     ret = rockchip_iodomain_write(supply, uV);
>> +     if (ret && event == REGULATOR_EVENT_PRE_VOLTAGE_CHANGE)
>> +             return NOTIFY_BAD;
>> +
>> +     dev_info(supply->iod->dev, "Setting to %d done\n", uV);
>> +     return NOTIFY_OK;
>> +}
>> +
>> +#define RK3288_SOC_CON2                      0x24c
>> +#define RK3288_SOC_CON2_FLASH0               BIT(7)
>> +#define RK3288_SOC_FLASH_SUPPLY_NUM  2
>> +
> Not a strong opinion but you can club all the defines on top
> of the file.

Sure, I'll move them.

-Doug
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