Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752206AbaGKBpx (ORCPT ); Thu, 10 Jul 2014 21:45:53 -0400 Received: from bhuna.collabora.co.uk ([93.93.135.160]:42583 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751721AbaGKBpv (ORCPT ); Thu, 10 Jul 2014 21:45:51 -0400 Message-ID: <53BF41C8.4080304@collabora.co.uk> Date: Fri, 11 Jul 2014 03:45:44 +0200 From: Javier Martinez Canillas User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Icedove/24.5.0 MIME-Version: 1.0 To: amit daniel kachhap CC: Lee Jones , Alessandro Zummo , Krzysztof Kozlowski , Kukjin Kim , Mike Turquette , Tomeu Vizoso , devicetree@vger.kernel.org, Yadwinder Singh Brar , "linux-kernel@vger.kernel.org" , Liam Girdwood , Doug Anderson , Tushar Behera , Mark Brown , "linux-samsung-soc@vger.kernel.org" , Olof Johansson , Andreas Farber , LAK Subject: Re: [PATCH v7 08/24] mfd: max77686: Add Dynamic Voltage Scaling (DVS) support References: <1404505467-26526-1-git-send-email-javier.martinez@collabora.co.uk> <1404505467-26526-9-git-send-email-javier.martinez@collabora.co.uk> In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Amit, On 07/10/2014 11:59 AM, amit daniel kachhap wrote: > On Sat, Jul 5, 2014 at 1:54 AM, Javier Martinez Canillas > wrote: >> Some regulators on the MAX77686 PMIC have Dynamic Voltage Scaling >> (DVS) support that allows output voltage to change dynamically. >> >> For MAX77686, these regulators are Buck regulators 2, 3 and 4. >> >> Each Buck output voltage is selected using a set of external >> inputs: DVS1-3 and SELB2-4. >> >> DVS registers can be used to configure the output voltages for each >> Buck regulator and which one is active is controled by DVSx lines. >> >> SELBx lines are used to control if individual Buck lines are ON or OFF. >> >> This patch adds support to configure the DVSx and SELBx lines >> from DT and to setup and read the GPIO lines connected to them. > > The entire series looks nice. Few minor comments from my side. I guess > still one more version in needed as per other ppls comment. > You may add, > Reviewed-by: Amit Daniel Kachhap > Thanks. >> >> Signed-off-by: Javier Martinez Canillas >> Reviewed-by: Krzysztof Kozlowski >> --- >> >> Changes since v6: >> - Add a comment that max77686_read_gpios() function can sleep. >> Sugggested by Krzysztof Kozlowski >> --- >> drivers/mfd/max77686.c | 119 +++++++++++++++++++++++++++++++++++++++++++ >> include/linux/mfd/max77686.h | 18 ++++--- >> 2 files changed, 129 insertions(+), 8 deletions(-) >> >> diff --git a/drivers/mfd/max77686.c b/drivers/mfd/max77686.c >> index 8650832..d193873 100644 >> --- a/drivers/mfd/max77686.c >> +++ b/drivers/mfd/max77686.c >> @@ -32,8 +32,10 @@ >> #include >> #include >> #include >> +#include >> #include >> #include >> +#include >> >> #define I2C_ADDR_RTC (0x0C >> 1) >> >> @@ -101,9 +103,119 @@ static const struct of_device_id max77686_pmic_dt_match[] = { >> {}, >> }; >> >> +static void max77686_dt_parse_dvs_gpio(struct device *dev) >> +{ >> + struct max77686_platform_data *pd = dev_get_platdata(dev); >> + int i; >> + >> + /* >> + * NOTE: we don't consider GPIO errors fatal; board may have some lines >> + * directly pulled high or low and thus doesn't specify them. >> + */ >> + for (i = 0; i < ARRAY_SIZE(pd->buck_gpio_dvs); i++) >> + pd->buck_gpio_dvs[i] = >> + devm_gpiod_get_index(dev, "max77686,pmic-buck-dvs", i); >> + >> + for (i = 0; i < ARRAY_SIZE(pd->buck_gpio_selb); i++) >> + pd->buck_gpio_selb[i] = >> + devm_gpiod_get_index(dev, "max77686,pmic-buck-selb", i); >> +} >> + >> +/** >> + * max77686_setup_gpios() - init DVS-related GPIOs >> + * @dev: device whose platform data contains the dvs GPIOs information >> + * >> + * This function claims / initalizations GPIOs related to DVS if they are >> + * defined. This may have the effect of switching voltages if the >> + * pdata->buck_default_idx does not match the boot time state of pins. >> + */ >> +int max77686_setup_gpios(struct device *dev) >> +{ >> + struct max77686_platform_data *pd = dev_get_platdata(dev); >> + int buck_default_idx = pd->buck_default_idx; >> + int ret; >> + int i; >> + >> + /* Set all SELB high to avoid glitching while DVS is changing */ >> + for (i = 0; i < ARRAY_SIZE(pd->buck_gpio_selb); i++) { >> + struct gpio_desc *gpio = pd->buck_gpio_selb[i]; >> + >> + /* OK if some GPIOs aren't defined */ >> + if (IS_ERR(gpio)) >> + continue; >> + >> + ret = gpiod_direction_output_raw(gpio, 1); >> + if (ret) { >> + dev_err(dev, "can't set gpio[%d] dir: %d\n", i, ret); >> + return ret; >> + } >> + } >> + >> + /* Set our initial setting */ >> + for (i = 0; i < ARRAY_SIZE(pd->buck_gpio_dvs); i++) { >> + struct gpio_desc *gpio = pd->buck_gpio_dvs[i]; >> + >> + /* OK if some GPIOs aren't defined */ >> + if (IS_ERR(gpio)) >> + continue; >> + >> + /* If a GPIO is valid, set it */ >> + gpiod_direction_output(gpio, (buck_default_idx >> i) & 1); >> + if (ret) { >> + dev_err(dev, "can't set gpio[%d]: dir %d\n", i, ret); >> + return ret; >> + } >> + } >> + >> + /* Now set SELB low to take effect */ >> + for (i = 0; i < ARRAY_SIZE(pd->buck_gpio_selb); i++) { >> + struct gpio_desc *gpio = pd->buck_gpio_selb[i]; >> + >> + if (!IS_ERR(gpio)) >> + gpiod_set_value(gpio, 0); >> + } >> + >> + return 0; >> +} >> +EXPORT_SYMBOL_GPL(max77686_setup_gpios); >> + >> +/** >> + * max77686_read_gpios() - read the current state of the dvs GPIOs >> + * @pdata: platform data that contains the dvs GPIOs information >> + * >> + * We call this function at bootup to detect what slot the firmware was >> + * using for the DVS GPIOs. That way we can properly preserve the firmware's >> + * voltage settings >> + * >> + * This function can sleep so must not be called from atomic context. >> + */ >> +int max77686_read_gpios(struct max77686_platform_data *pdata) >> +{ >> + int buck_default_idx = pdata->buck_default_idx; >> + int result = 0; >> + int i; >> + >> + for (i = 0; i < ARRAY_SIZE(pdata->buck_gpio_dvs); i++) { >> + struct gpio_desc *gpio = pdata->buck_gpio_dvs[i]; >> + >> + /* OK if some GPIOs aren't defined; we'll use default */ >> + if (IS_ERR(gpio)) { >> + result |= buck_default_idx & (1 << i); >> + continue; >> + } >> + >> + if (gpiod_get_value_cansleep(gpio)) >> + result |= 1 << i; >> + } >> + >> + return result; >> +} >> +EXPORT_SYMBOL_GPL(max77686_read_gpios); >> + >> static struct max77686_platform_data *max77686_i2c_parse_dt_pdata(struct device >> *dev) >> { >> + struct device_node *np = dev->of_node; >> struct max77686_platform_data *pd; >> >> pd = devm_kzalloc(dev, sizeof(*pd), GFP_KERNEL); >> @@ -111,6 +223,13 @@ static struct max77686_platform_data *max77686_i2c_parse_dt_pdata(struct device >> return NULL; >> >> dev->platform_data = pd; >> + >> + /* Read default index and ignore errors, since default is 0 */ >> + of_property_read_u32(np, "max77686,pmic-buck-default-dvs-idx", >> + &pd->buck_default_idx); > Any error checking code here. Say if pmic-buck-default-dvs-idx exceed 8? I'm not a DT expert but AFAIK the kernel should expect the data in a FDT to be correct and should not validate it on runtime. There is work-in-progress to add a proper schema checking for DTS to the dtc so on build time it can be validated that a DTS is valid. AFAIU the only thing that the kernel should check is if a required property does not exist. >> + >> + max77686_dt_parse_dvs_gpio(dev); >> + >> return pd; >> } >> >> diff --git a/include/linux/mfd/max77686.h b/include/linux/mfd/max77686.h >> index 4cbcc13..46a736b 100644 >> --- a/include/linux/mfd/max77686.h >> +++ b/include/linux/mfd/max77686.h >> @@ -99,15 +99,17 @@ struct max77686_platform_data { >> struct max77686_opmode_data *opmode_data; >> >> /* >> - * GPIO-DVS feature is not enabled with the current version of >> - * MAX77686 driver. Buck2/3/4_voltages[0] is used as the default >> - * voltage at probe. DVS/SELB gpios are set as OUTPUT-LOW. >> + * GPIO-DVS feature is not fully enabled with the current version of >> + * MAX77686 driver, but the driver does support using a DVS index other >> + * than the default of 0. >> */ >> - int buck234_gpio_dvs[3]; /* GPIO of [0]DVS1, [1]DVS2, [2]DVS3 */ >> - int buck234_gpio_selb[3]; /* [0]SELB2, [1]SELB3, [2]SELB4 */ >> - unsigned int buck2_voltage[8]; /* buckx_voltage in uV */ >> - unsigned int buck3_voltage[8]; >> - unsigned int buck4_voltage[8]; > I think when DVS gpio is used all the 8 voltage levels are fetched > from DT during booting and the registers are programmed accordingly. > Any further set/get_voltage just changes the GPIO lines. > Any reason why this method is not used? What are you describing is how the DT binding works for other Maxim PMICs that also have DVS support right? (e.g: max8997). The DVS binding in max77686/802 is actually a subset of the one in max8997 so it let's you only choose which single DVS index is going to be used. The GPIOs in "max77686,pmic-buck-dvs-gpios" should match "pmic-buck-default-dvs-idx". To be honest I just took the DT binding that was used in the max77xxx driver from the Chrome OS 3.8 kernel and didn't compare it with other Maxim PMICs DT bingings. I wonder if I should just take the DVS patches out from this initial version to avoid blocking the max77802 support and then we can discuss this in more detail. >> + struct gpio_desc *buck_gpio_dvs[3]; /* GPIO of [0]DVS1, [1]DVS2, [2]DVS3 */ >> + int buck_default_idx; /* Default value of DVS1, 2, 3 */ >> + >> + struct gpio_desc *buck_gpio_selb[3]; /* Buck regulators 2, 3, 4 */ >> }; >> >> +extern int max77686_setup_gpios(struct device *dev); >> +extern int max77686_read_gpios(struct max77686_platform_data *pdata); >> + >> #endif /* __LINUX_MFD_MAX77686_H */ >> -- >> 2.0.0.rc2 >> Best regards, Javier -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/