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Date:	Thu, 30 Apr 2015 01:36:18 +0900
From:	Chanwoo Choi <cwchoi00@...il.com>
To:	Ramakrishna Pallala <ramakrishna.pallala@...el.com>
Cc:	linux-kernel <linux-kernel@...r.kernel.org>,
	Lee Jones <lee.jones@...aro.org>,
	Samuel Ortiz <sameo@...ux.intel.com>,
	Jacob Pan <jacob.jun.pan@...ux.intel.com>
Subject: Re: [PATCH v7] extcon-axp288: Add axp288 extcon driver support

Hi Ram,

I added my comment.

On Wed, Apr 29, 2015 at 11:22 AM, Ramakrishna Pallala
<ramakrishna.pallala@...el.com> wrote:
> This patch adds the extcon support for AXP288 PMIC which
> has the BC1.2 charger detection capability. Additionally
> it also adds the USB mux switching support b/w SOC and PMIC
> based on GPIO control.
>
> Signed-off-by: Ramakrishna Pallala <ramakrishna.pallala@...el.com>
> ---
>  drivers/extcon/Kconfig         |    7 +
>  drivers/extcon/Makefile        |    1 +
>  drivers/extcon/extcon-axp288.c |  403 ++++++++++++++++++++++++++++++++++++++++
>  include/linux/mfd/axp20x.h     |    5 +
>  4 files changed, 416 insertions(+)
>  create mode 100644 drivers/extcon/extcon-axp288.c
>
> diff --git a/drivers/extcon/Kconfig b/drivers/extcon/Kconfig
> index fdc0bf0..2305edc 100644
> --- a/drivers/extcon/Kconfig
> +++ b/drivers/extcon/Kconfig
> @@ -28,6 +28,13 @@ config EXTCON_ARIZONA
>           with Wolfson Arizona devices. These are audio CODECs with
>           advanced audio accessory detection support.
>
> +config EXTCON_AXP288
> +       tristate "X-Power AXP288 EXTCON support"
> +       depends on MFD_AXP20X && USB_PHY
> +       help
> +         Say Y here to enable support for USB peripheral detection
> +         and USB MUX switching by X-Power AXP288 PMIC.
> +
>  config EXTCON_GPIO
>         tristate "GPIO extcon support"
>         depends on GPIOLIB
> diff --git a/drivers/extcon/Makefile b/drivers/extcon/Makefile
> index 9204114..ba787d0 100644
> --- a/drivers/extcon/Makefile
> +++ b/drivers/extcon/Makefile
> @@ -5,6 +5,7 @@
>  obj-$(CONFIG_EXTCON)           += extcon.o
>  obj-$(CONFIG_EXTCON_ADC_JACK)  += extcon-adc-jack.o
>  obj-$(CONFIG_EXTCON_ARIZONA)   += extcon-arizona.o
> +obj-$(CONFIG_EXTCON_AXP288)    += extcon-axp288.o
>  obj-$(CONFIG_EXTCON_GPIO)      += extcon-gpio.o
>  obj-$(CONFIG_EXTCON_MAX14577)  += extcon-max14577.o
>  obj-$(CONFIG_EXTCON_MAX77693)  += extcon-max77693.o
> diff --git a/drivers/extcon/extcon-axp288.c b/drivers/extcon/extcon-axp288.c
> new file mode 100644
> index 0000000..7d72d44
> --- /dev/null
> +++ b/drivers/extcon/extcon-axp288.c
> @@ -0,0 +1,403 @@
> +/*
> + * extcon-axp288.c - X-Power AXP288 PMIC extcon cable detection driver
> + *
> + * Copyright (C) 2014 Intel Corporation

2014 -> 2015

> + * Author: Ramakrishna Pallala <ramakrishna.pallala@...el.com>
> + *
> + * 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/module.h>
> +#include <linux/kernel.h>
> +#include <linux/io.h>
> +#include <linux/slab.h>
> +#include <linux/interrupt.h>
> +#include <linux/platform_device.h>
> +#include <linux/property.h>
> +#include <linux/usb/phy.h>
> +#include <linux/notifier.h>
> +#include <linux/extcon.h>
> +#include <linux/regmap.h>
> +#include <linux/gpio.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/mfd/axp20x.h>
> +
> +/* Power source status register */
> +#define PS_STAT_VBUS_TRIGGER           BIT(0)
> +#define PS_STAT_BAT_CHRG_DIR           BIT(2)
> +#define PS_STAT_VBUS_ABOVE_VHOLD       BIT(3)
> +#define PS_STAT_VBUS_VALID             BIT(4)
> +#define PS_STAT_VBUS_PRESENT           BIT(5)
> +
> +/* BC module global register */
> +#define BC_GLOBAL_RUN                  BIT(0)
> +#define BC_GLOBAL_DET_STAT             BIT(2)
> +#define BC_GLOBAL_DBP_TOUT             BIT(3)
> +#define BC_GLOBAL_VLGC_COM_SEL         BIT(4)
> +#define BC_GLOBAL_DCD_TOUT_MASK                (BIT(6)|BIT(5))
> +#define BC_GLOBAL_DCD_TOUT_300MS       0
> +#define BC_GLOBAL_DCD_TOUT_100MS       1
> +#define BC_GLOBAL_DCD_TOUT_500MS       2
> +#define BC_GLOBAL_DCD_TOUT_900MS       3
> +#define BC_GLOBAL_DCD_DET_SEL          BIT(7)
> +
> +/* BC module vbus control and status register */
> +#define VBUS_CNTL_DPDM_PD_EN           BIT(4)
> +#define VBUS_CNTL_DPDM_FD_EN           BIT(5)
> +#define VBUS_CNTL_FIRST_PO_STAT                BIT(6)
> +
> +/* BC USB status register */
> +#define USB_STAT_BUS_STAT_MASK         (BIT(3)|BIT(2)|BIT(1)|BIT(0))
> +#define USB_STAT_BUS_STAT_SHIFT                0
> +#define USB_STAT_BUS_STAT_ATHD         0
> +#define USB_STAT_BUS_STAT_CONN         1
> +#define USB_STAT_BUS_STAT_SUSP         2
> +#define USB_STAT_BUS_STAT_CONF         3
> +#define USB_STAT_USB_SS_MODE           BIT(4)
> +#define USB_STAT_DEAD_BAT_DET          BIT(6)
> +#define USB_STAT_DBP_UNCFG             BIT(7)
> +
> +/* BC detect status register */
> +#define DET_STAT_MASK                  (BIT(7)|BIT(6)|BIT(5))
> +#define DET_STAT_SHIFT                 5
> +#define DET_STAT_SDP                   1
> +#define DET_STAT_CDP                   2
> +#define DET_STAT_DCP                   3
> +
> +/* IRQ enable-1 register */
> +#define PWRSRC_IRQ_CFG_MASK            (BIT(4)|BIT(3)|BIT(2))
> +
> +/* IRQ enable-6 register */
> +#define BC12_IRQ_CFG_MASK              BIT(1)
> +
> +#define AXP288_EXTCON_SLOW_CHARGER             "SLOW-CHARGER"
> +#define AXP288_EXTCON_DOWNSTREAM_CHARGER       "CHARGE-DOWNSTREAM"
> +#define AXP288_EXTCON_FAST_CHARGER             "FAST-CHARGER"
> +
> +enum axp288_extcon_reg {
> +       AXP288_PS_STAT_REG              = 0x00,
> +       AXP288_PS_BOOT_REASON_REG       = 0x02,
> +       AXP288_BC_GLOBAL_REG            = 0x2c,
> +       AXP288_BC_VBUS_CNTL_REG         = 0x2d,
> +       AXP288_BC_USB_STAT_REG          = 0x2e,
> +       AXP288_BC_DET_STAT_REG          = 0x2f,
> +       AXP288_PWRSRC_IRQ_CFG_REG       = 0x40,
> +       AXP288_BC12_IRQ_CFG_REG         = 0x45,
> +};
> +
> +enum axp288_mux_select {
> +       EXTCON_GPIO_MUX_SEL_PMIC = 0,
> +       EXTCON_GPIO_MUX_SEL_SOC,
> +};
> +
> +enum axp288_extcon_irq {
> +       VBUS_FALLING_IRQ = 0,
> +       VBUS_RISING_IRQ,
> +       MV_CHNG_IRQ,
> +       BC_USB_CHNG_IRQ,
> +       EXTCON_IRQ_END,
> +};
> +
> +static const char *axp288_extcon_cables[] = {
> +       AXP288_EXTCON_SLOW_CHARGER,
> +       AXP288_EXTCON_DOWNSTREAM_CHARGER,
> +       AXP288_EXTCON_FAST_CHARGER,
> +       NULL,
> +};
> +
> +struct axp288_extcon_info {
> +       struct device *dev;
> +       struct regmap *regmap;
> +       struct regmap_irq_chip_data *regmap_irqc;
> +       struct axp288_extcon_pdata *pdata;
> +       int irq[EXTCON_IRQ_END];
> +       struct extcon_dev *edev;
> +       struct notifier_block extcon_nb;
> +       struct usb_phy *otg;
> +};
> +
> +/* Power up/down reason string array */
> +static char *axp288_pwr_up_down_info[] = {
> +       "Last wake caused by user pressing the power button",
> +       "Last wake caused by a charger insertion",
> +       "Last wake caused by a battery insertion",
> +       "Last wake caused by SOC initiated global reset",
> +       "Last wake caused by cold reset",
> +       "Last shutdown caused by PMIC UVLO threshold",
> +       "Last shutdown caused by SOC initiated cold off",
> +       "Last shutdown caused by user pressing the power button",
> +       NULL,
> +};
> +
> +/*
> + * Decode and log the given "reset source indicator" (rsi)
> + * register and then clear it.
> + */
> +static void axp288_extcon_log_rsi(struct axp288_extcon_info *info)
> +{
> +       char **rsi;
> +       unsigned int val, i, clear_mask = 0;
> +       int ret;
> +
> +       ret = regmap_read(info->regmap, AXP288_PS_BOOT_REASON_REG, &val);
> +       for (i = 0, rsi = axp288_pwr_up_down_info; *rsi; rsi++, i++) {
> +               if (val & BIT(i)) {
> +                       dev_dbg(info->dev, "%s\n", *rsi);
> +                       clear_mask |= BIT(i);
> +               }
> +       }
> +
> +       /* Clear the register value for next reboot (write 1 to clear bit) */
> +       regmap_write(info->regmap, AXP288_PS_BOOT_REASON_REG, clear_mask);
> +}
> +
> +static int handle_chrg_det_event(struct axp288_extcon_info *info)

Add 'axp288' prefix to function name as following:
- handle_chrg_det_event -> axp288_handle_chrg_det_event

> +{
> +       static bool notify_otg, notify_charger;
> +       static char *cable;
> +       int ret, stat, cfg, pwr_stat;
> +       u8 chrg_type;
> +       bool vbus_attach = false;
> +
> +       ret = regmap_read(info->regmap, AXP288_PS_STAT_REG, &pwr_stat);
> +       if (ret < 0) {
> +               dev_err(info->dev, "vbus status read error\n");

I recommend that you use the consistency log pattern as following:
            "failed to read vbus status\n"

> +               return ret;
> +       }
> +
> +       vbus_attach = (pwr_stat & PS_STAT_VBUS_PRESENT);
> +       if (vbus_attach) {
> +               dev_dbg(info->dev, "vbus present\n");
> +       } else {
> +               dev_dbg(info->dev, "vbus not present\n");
> +               goto notify_otg;
> +       }

I think that you can simplify upper if/else statement as following
without any unneeded debug log.
             if (!vbus_attach) {
                     goto notify_otg;

> +
> +       /* Check charger detection completion status */
> +       ret = regmap_read(info->regmap, AXP288_BC_GLOBAL_REG, &cfg);
> +       if (ret < 0)
> +               goto dev_det_ret;
> +       if (cfg & BC_GLOBAL_DET_STAT) {
> +               dev_dbg(info->dev, "charger detection not complete!!\n");

ditto. Don't need to add '!' at the end of log message.
"charger detection not complete!!\n" -> "can't complete the charger detection\n"

> +               goto dev_det_ret;
> +       }
> +
> +       ret = regmap_read(info->regmap, AXP288_BC_DET_STAT_REG, &stat);
> +       if (ret < 0)
> +               goto dev_det_ret;
> +       dev_dbg(info->dev, "stat:%x, cfg:%x\n", stat, cfg);

I don't prefer to show the just register value without any log message.

> +
> +       chrg_type = (stat & DET_STAT_MASK) >> DET_STAT_SHIFT;
> +
> +       if (chrg_type == DET_STAT_SDP) {
> +               dev_dbg(info->dev, "sdp cable connecetd\n");

 "sdp cable connecetd\n"-> "sdp cable is connected\n"

> +               notify_otg = true;
> +               notify_charger = true;
> +               cable = AXP288_EXTCON_SLOW_CHARGER;
> +       } else if (chrg_type == DET_STAT_CDP) {
> +               dev_dbg(info->dev, "cdp cable connecetd\n");

"cdp cable connecetd\n" -> "cdp cable is connected"

> +               notify_otg = true;
> +               notify_charger = true;
> +               cable = AXP288_EXTCON_DOWNSTREAM_CHARGER;
> +       } else if (chrg_type == DET_STAT_DCP) {
> +               dev_dbg(info->dev, "dcp cable connecetd\n");

"dcp cable connecetd\n" -> "dcp cable is connecetd\n"

> +               notify_charger = true;
> +               cable = AXP288_EXTCON_FAST_CHARGER;
> +       } else {
> +               dev_warn(info->dev,
> +                       "disconnect or unknown or ID event\n");
> +       }

How about using the 'switch' statement instead of 'if/else'?

> +
> +notify_otg:
> +       if (notify_otg) {
> +               /*
> +                * If VBUS is absent Connect D+/D- lines to PMIC for BC
> +                * detection. Else connect them to SOC for USB communication.
> +                */
> +               if (info->pdata->gpio_mux_cntl)
> +                       gpiod_set_value(info->pdata->gpio_mux_cntl,
> +                               vbus_attach ? EXTCON_GPIO_MUX_SEL_SOC
> +                                               : EXTCON_GPIO_MUX_SEL_PMIC);
> +
> +               atomic_notifier_call_chain(&info->otg->notifier,
> +                       vbus_attach ? USB_EVENT_VBUS : USB_EVENT_NONE, NULL);
> +       }
> +
> +       if (notify_charger)
> +               extcon_set_cable_state(info->edev, cable, vbus_attach);
> +
> +       /* Clear the flags on disconnect event */
> +       if (!vbus_attach) {
> +               notify_otg = false;
> +               notify_charger = false;
> +       }

You better to modify if statement as following without brace:
            if (!vbus_attach)
                  notify_otg = notify_charger = false;

> +
> +       return 0;
> +
> +dev_det_ret:
> +       if (ret < 0)
> +               dev_warn(info->dev, "BC Mod detection error\n");

Use the dev_err() instead of dev_warn() because log message means error state.

> +
> +       return ret;
> +}
> +
> +static irqreturn_t axp288_extcon_isr(int irq, void *data)
> +{
> +       struct axp288_extcon_info *info = data;
> +       unsigned int i;
> +       int ret;
> +
> +       for (i = 0; i < EXTCON_IRQ_END; i++) {
> +               if (info->irq[i] == irq)
> +                       break;
> +       }
> +
> +       if (i == EXTCON_IRQ_END) {
> +               dev_warn(info->dev, "spurious interrupt!!\n");

for and if statement is not necessary because 'int irq' must be included
in 'info->irq[]' array.

> +               return IRQ_NONE;
> +       }
> +
> +       ret = handle_chrg_det_event(info);

ditto.
- axp288_handle_chrg_det_event()

> +       if (ret < 0)
> +               dev_warn(info->dev, "error in PWRSRC INT handling\n");

Use the 'dev_err' instead of 'dev_warn' and modify the log message on
upper comment.
        "failed to handle PWRSRC interrupt\n"

> +
> +       return IRQ_HANDLED;
> +}
> +
> +static void axp288_extcon_enable_irq(struct axp288_extcon_info *info)
> +{
> +       /* Unmask VBUS interrupt */
> +       regmap_write(info->regmap, AXP288_PWRSRC_IRQ_CFG_REG,
> +                                               PWRSRC_IRQ_CFG_MASK);
> +       regmap_update_bits(info->regmap, AXP288_BC_GLOBAL_REG,
> +                                               BC_GLOBAL_RUN, 0);
> +       /* Unmask the BC1.2 complte interrupts */

complte? complete?

> +       regmap_write(info->regmap, AXP288_BC12_IRQ_CFG_REG, BC12_IRQ_CFG_MASK);
> +       /* Enable the charger detection logic */
> +       regmap_update_bits(info->regmap, AXP288_BC_GLOBAL_REG,
> +                                       BC_GLOBAL_RUN, BC_GLOBAL_RUN);
> +}
> +
> +static int axp288_extcon_probe(struct platform_device *pdev)
> +{
> +       struct axp288_extcon_info *info;
> +       struct axp20x_dev *axp20x = dev_get_drvdata(pdev->dev.parent);
> +       int ret, i, pirq, gpio;
> +
> +       info = devm_kzalloc(&pdev->dev, sizeof(*info), GFP_KERNEL);
> +       if (!info)
> +               return -ENOMEM;
> +
> +       info->dev = &pdev->dev;
> +       info->regmap = axp20x->regmap;
> +       info->regmap_irqc = axp20x->regmap_irqc;
> +       info->pdata = pdev->dev.platform_data;
> +
> +       if (!info->pdata) {
> +               /* TODO: Try ACPI provided pdata via device properties */

I prefer to remove "TODO" comment.

> +               if (!device_property_present(&pdev->dev,
> +                                       "axp288_extcon_data\n"))
> +                       dev_err(&pdev->dev, "no platform data\n");

ditto.
- "failed to get platform data'

> +               return -ENODEV;
> +       }
> +       platform_set_drvdata(pdev, info);
> +
> +       axp288_extcon_log_rsi(info);
> +
> +       /* Initialize extcon device */
> +       info->edev = devm_extcon_dev_allocate(&pdev->dev,
> +                                             axp288_extcon_cables);
> +       if (IS_ERR(info->edev)) {
> +               dev_err(&pdev->dev, "failed to allocate memory for extcon\n");
> +               ret = PTR_ERR(info->edev);
> +               return ret;

Return 'PTR_ERR(info->edev)' directly without allocation to 'ret' variable.

> +       }
> +
> +       /* Register extcon device */
> +       ret = devm_extcon_dev_register(&pdev->dev, info->edev);
> +       if (ret) {
> +               dev_err(&pdev->dev, "failed to register extcon device\n");
> +               return ret;
> +       }
> +
> +       /* Get otg transceiver phy */
> +       info->otg = usb_get_phy(USB_PHY_TYPE_USB2);
> +       if (IS_ERR(info->otg)) {
> +               dev_warn(&pdev->dev, "failed to get otg transceiver\n");
> +               ret = PTR_ERR(info->otg);
> +               return ret;

ditto.

> +       }
> +
> +       /* Set up gpio control for USB Mux */
> +       if (info->pdata->gpio_mux_cntl) {
> +               gpio = desc_to_gpio(info->pdata->gpio_mux_cntl);
> +               ret = gpio_request(gpio, "USB_MUX");
> +               if (ret < 0) {
> +                       dev_err(&pdev->dev,
> +                               "failed to request the gpio=%d\n", gpio);
> +                       goto gpio_req_failed;
> +               }
> +               gpiod_direction_output(info->pdata->gpio_mux_cntl,
> +                                               EXTCON_GPIO_MUX_SEL_PMIC);
> +       }
> +
> +       for (i = 0; i < EXTCON_IRQ_END; i++) {
> +               pirq = platform_get_irq(pdev, i);
> +               info->irq[i] = regmap_irq_get_virq(info->regmap_irqc, pirq);
> +               if (info->irq[i] < 0) {
> +                       dev_warn(&pdev->dev,
> +                               "regmap_irq get virq failed for IRQ %d: %d\n",

I recommend that you use the consistency log pattern as following:
           "failed to get virtual interrupt ..."

> +                               pirq, info->irq[i]);
> +                       info->irq[i] = -1;
> +                       goto intr_reg_failed;

Use 'gpio_req_failed' instead of 'intr_reg_failed'.

> +               }
> +
> +               ret = devm_request_threaded_irq(&pdev->dev, info->irq[i],
> +                               NULL, axp288_extcon_isr,
> +                               IRQF_ONESHOT | IRQF_NO_SUSPEND,
> +                               pdev->name, info);
> +               if (ret) {
> +                       dev_err(&pdev->dev, "request_irq fail :%d err:%d\n",

ditto. "failed to request interrupt

> +                                                       info->irq[i], ret);
> +                       goto intr_reg_failed;

Use 'gpio_req_failed' instead of 'intr_reg_failed'.

> +               }
> +       }
> +
> +       /* Enable interrupts */
> +       axp288_extcon_enable_irq(info);
> +
> +       return 0;
> +
> +intr_reg_failed:

'intr_reg_failed' is not necessary. I prefer to remove it.

> +gpio_req_failed:
> +       usb_put_phy(info->otg);
> +       return ret;
> +}
> +
> +static int axp288_extcon_remove(struct platform_device *pdev)
> +{
> +       struct axp288_extcon_info *info = platform_get_drvdata(pdev);
> +
> +       usb_put_phy(info->otg);
> +       return 0;
> +}
> +
> +static struct platform_driver axp288_extcon_driver = {
> +       .probe = axp288_extcon_probe,
> +       .remove = axp288_extcon_remove,
> +       .driver = {
> +               .name = "axp288_extcon",
> +       },
> +};
> +module_platform_driver(axp288_extcon_driver);
> +
> +MODULE_AUTHOR("Ramakrishna Pallala <ramakrishna.pallala@...el.com>");
> +MODULE_DESCRIPTION("X-Powers AXP288 extcon driver");
> +MODULE_LICENSE("GPL v2");
> diff --git a/include/linux/mfd/axp20x.h b/include/linux/mfd/axp20x.h
> index dfabd6d..4ed8071 100644
> --- a/include/linux/mfd/axp20x.h
> +++ b/include/linux/mfd/axp20x.h
> @@ -275,4 +275,9 @@ struct axp20x_fg_pdata {
>         int thermistor_curve[MAX_THERM_CURVE_SIZE][2];
>  };
>
> +struct axp288_extcon_pdata {
> +       /* GPIO pin control to switch D+/D- lines b/w PMIC and SOC */
> +       struct gpio_desc *gpio_mux_cntl;
> +};
> +
>  #endif /* __LINUX_MFD_AXP20X_H */

Thanks,
Chanwoo Choi
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