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Date: Wed, 1 Sep 2010 10:54:21 -0700
From: Rhyland Klein <rklein@...dia.com>
To: Jean Delvare <khali@...ux-fr.org>
CC: "cbouatmailru@...il.com" <cbouatmailru@...il.com>,
"linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"olof@...om.net" <olof@...om.net>, Andrew Chew <AChew@...dia.com>
Subject: RE: [PATCH 1/1] power supply: add driver for TI BQ20Z75 gas gauge IC
Thanks for the review, fixed up what you suggested, I did leave one place as -EINVAL as it seemed the most appropriate for the spot. Will repost soon.
-----Original Message-----
From: Jean Delvare [mailto:khali@...ux-fr.org]
Sent: Tuesday, August 31, 2010 1:24 AM
To: Rhyland Klein
Cc: cbouatmailru@...il.com; linux-i2c@...r.kernel.org; linux-kernel@...r.kernel.org; olof@...om.net; Andrew Chew
Subject: Re: [PATCH 1/1] power supply: add driver for TI BQ20Z75 gas gauge IC
Hi Rhyland,
On Fri, 27 Aug 2010 15:50:43 -0700, rklein@...dia.com wrote:
> From: Rhyland Klein <rklein@...dia.com>
>
> this driver depends on I2C and uses SMBUS for communication with the host.
Quick review (I am not familiar with the power supply API):
> Signed-off-by: Rhyland Klein <rklein@...dia.com>
> ---
> drivers/power/Kconfig | 7 +
> drivers/power/Makefile | 1 +
> drivers/power/bq20z75.c | 403 +++++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 411 insertions(+), 0 deletions(-)
> create mode 100644 drivers/power/bq20z75.c
>
> diff --git a/drivers/power/Kconfig b/drivers/power/Kconfig
> index 8e9ba17..c72e628 100644
> --- a/drivers/power/Kconfig
> +++ b/drivers/power/Kconfig
> @@ -142,4 +142,11 @@ config CHARGER_PCF50633
> help
> Say Y to include support for NXP PCF50633 Main Battery Charger.
>
> +config BQ20Z75_GASGAUGE
Following the naming used for other options in this menu, this would be
BATTERY_BQ20Z75.
-Done
> + tristate "TI BQ20Z75 GAS GAUGE"
Not all capitals, please.
-Fixed, changed to "TI BQ20z75 gas gauge"
> + depends on I2C
> + help
> + Say Y to include support for TI BQ20Z75 SBS-compliant
> + gas gauge and protection IC.
> +
> endif # POWER_SUPPLY
> diff --git a/drivers/power/Makefile b/drivers/power/Makefile
> index 0005080..98abc31 100644
> --- a/drivers/power/Makefile
> +++ b/drivers/power/Makefile
> @@ -34,3 +34,4 @@ obj-$(CONFIG_BATTERY_DA9030) += da9030_battery.o
> obj-$(CONFIG_BATTERY_MAX17040) += max17040_battery.o
> obj-$(CONFIG_BATTERY_Z2) += z2_battery.o
> obj-$(CONFIG_CHARGER_PCF50633) += pcf50633-charger.o
> +obj-$(CONFIG_BQ20Z75_GASGAUGE) += bq20z75.o
> diff --git a/drivers/power/bq20z75.c b/drivers/power/bq20z75.c
> new file mode 100644
> index 0000000..4eb6638
> --- /dev/null
> +++ b/drivers/power/bq20z75.c
> @@ -0,0 +1,403 @@
> +/*
> + * drivers/power/bq20z75.c
Please remove, this doesn't add much value and is likely to get
outdated at some point.
-Done
> + *
> + * Gas Gauge driver for TI's BQ20Z75
> + *
> + * Copyright (c) 2010, NVIDIA Corporation.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * 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.
> + *
> + * You should have received a copy of the GNU General Public License along
> + * with this program; if not, write to the Free Software Foundation, Inc.,
> + * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
> + */
> +
> +#include <linux/init.h>
> +#include <linux/module.h>
> +#include <linux/kernel.h>
> +#include <linux/err.h>
> +#include <linux/debugfs.h>
I don't think you need this one?
-Removed.
> +#include <linux/power_supply.h>
> +#include <linux/i2c.h>
> +#include <linux/slab.h>
> +
> +enum {
> + REG_MANUFACTURER_DATA,
> + REG_TEMPERATURE,
> + REG_VOLTAGE,
> + REG_CURRENT,
> + REG_CAPACITY,
> + REG_TIME_TO_EMPTY,
> + REG_TIME_TO_FULL,
> + REG_STATUS,
> + REG_CYCLE_COUNT,
> + REG_SERIAL_NUMBER,
> + REG_MAX
> +};
> +
> +#define BATTERY_MANUFACTURER_SIZE 12
> +#define BATTERY_NAME_SIZE 8
You don't use these anywhere?
-Removed
> +
> +/* manufacturer access defines */
> +#define MANUFACTURER_ACCESS_STATUS 0x0006
> +#define MANUFACTURER_ACCESS_SLEEP 0x0011
> +
> +/* battery status value bits */
> +#define BATTERY_CHARGING 0x40
> +#define BATTERY_FULL_CHARGED 0x20
> +#define BATTERY_FULL_DISCHARGED 0x10
> +
> +#define BQ20Z75_DATA(_psp, _addr, _min_value, _max_value) { \
> + .psp = _psp, \
> + .addr = _addr, \
> + .min_value = _min_value, \
> + .max_value = _max_value, \
> +}
> +
> +static struct bq20z75_device_data {
This could be const.
-Done
> + enum power_supply_property psp;
> + u8 addr;
> + int min_value;
> + int max_value;
> +} bq20z75_data[] = {
> + [REG_MANUFACTURER_DATA] =
> + BQ20Z75_DATA(POWER_SUPPLY_PROP_PRESENT, 0x00, 0, 65535),
> + [REG_TEMPERATURE] =
> + BQ20Z75_DATA(POWER_SUPPLY_PROP_TEMP, 0x08, 0, 65535),
> + [REG_VOLTAGE] =
> + BQ20Z75_DATA(POWER_SUPPLY_PROP_VOLTAGE_NOW, 0x09, 0, 20000),
> + [REG_CURRENT] =
> + BQ20Z75_DATA(POWER_SUPPLY_PROP_CURRENT_NOW, 0x0A, -32768, \
> + 32767),
You don't need the backslash at the end of the line.
-Removed
> + [REG_CAPACITY] =
> + BQ20Z75_DATA(POWER_SUPPLY_PROP_CAPACITY, 0x0e, 0, 100),
Please be consistent with case in hexadecimal numbers.
-Done
> + [REG_TIME_TO_EMPTY] =
> + BQ20Z75_DATA(POWER_SUPPLY_PROP_TIME_TO_EMPTY_AVG, 0x12, 0, \
> + 65535),
> + [REG_TIME_TO_FULL] =
> + BQ20Z75_DATA(POWER_SUPPLY_PROP_TIME_TO_FULL_AVG, 0x13, 0, \
> + 65535),
> + [REG_STATUS] =
> + BQ20Z75_DATA(POWER_SUPPLY_PROP_STATUS, 0x16, 0, 65535),
> + [REG_CYCLE_COUNT] =
> + BQ20Z75_DATA(POWER_SUPPLY_PROP_CYCLE_COUNT, 0x17, 0, 65535),
> + [REG_SERIAL_NUMBER] =
> + BQ20Z75_DATA(POWER_SUPPLY_PROP_SERIAL_NUMBER, 0x1C, 0, 65535),
> +};
> +
> +static enum power_supply_property bq20z75_properties[] = {
> + POWER_SUPPLY_PROP_STATUS,
> + POWER_SUPPLY_PROP_HEALTH,
> + POWER_SUPPLY_PROP_PRESENT,
> + POWER_SUPPLY_PROP_TECHNOLOGY,
> + POWER_SUPPLY_PROP_CYCLE_COUNT,
> + POWER_SUPPLY_PROP_VOLTAGE_NOW,
> + POWER_SUPPLY_PROP_CURRENT_NOW,
> + POWER_SUPPLY_PROP_CAPACITY,
> + POWER_SUPPLY_PROP_TEMP,
> + POWER_SUPPLY_PROP_TIME_TO_EMPTY_AVG,
> + POWER_SUPPLY_PROP_TIME_TO_FULL_AVG,
> + POWER_SUPPLY_PROP_SERIAL_NUMBER,
> +};
> +
> +static int bq20z75_get_property(struct power_supply *psy,
> + enum power_supply_property psp, union power_supply_propval *val);
> +
> +static struct power_supply bq20z75_supply = {
> + .name = "battery",
> + .type = POWER_SUPPLY_TYPE_BATTERY,
> + .properties = bq20z75_properties,
> + .num_properties = ARRAY_SIZE(bq20z75_properties),
> + .get_property = bq20z75_get_property,
> +};
> +
> +struct bq20z75_device_info {
> + struct i2c_client *client;
> +} *bq20z75_device;
This structure doesn't seem terribly useful. You typically need the
client to get to this information... And storing the device pointer as
a global is evil anyway, please don't do that.
TODO:
> +
> +static int bq20z75_get_battery_presence_and_health(
> + enum power_supply_property psp, union power_supply_propval *val)
> +{
> + s32 ret;
> +
> + /* Write to ManufacturerAccess with
> + * ManufacturerAccess command and then
> + * read the status */
> + ret = i2c_smbus_write_word_data(bq20z75_device->client,
> + bq20z75_data[REG_MANUFACTURER_DATA].addr,
> + MANUFACTURER_ACCESS_STATUS);
> + if (ret < 0) {
> + dev_err(&bq20z75_device->client->dev,
> + "%s: i2c write for battery presence failed\n",
> + __func__);
> + return -EINVAL;
> + }
> +
> + ret = i2c_smbus_read_word_data(bq20z75_device->client,
> + bq20z75_data[REG_MANUFACTURER_DATA].addr);
> + if (ret < 0) {
> + dev_err(&bq20z75_device->client->dev,
> + "%s: i2c read for battery presence failed\n",
> + __func__);
> + return -EINVAL;
> + }
-EINVAL doesn't look like the right error code. -ENODEV or -EIO would
seem more appropriate. Same issue several times, please address them
all.
-Done, only one place seemed to make sense for EINVAL, the default case where it was an unknown property, does that makes sense to you?
> +
> + if (ret < bq20z75_data[REG_MANUFACTURER_DATA].min_value ||
> + ret > bq20z75_data[REG_MANUFACTURER_DATA].max_value) {
> + val->intval = 0;
> + return 0;
> + }
> +
> + /* Mask the upper nibble of 2nd byte and
> + * lower byte of response then
> + * shift the result by 8 to get status*/
> + ret &= 0x0F00;
> + ret >>= 8;
> + if (psp == POWER_SUPPLY_PROP_PRESENT) {
> + if (ret == 0x0F)
> + /* battery removed */
> + val->intval = 0;
> + else
> + val->intval = 1;
> + } else if (psp == POWER_SUPPLY_PROP_HEALTH) {
> + if (ret == 0x09)
> + val->intval = POWER_SUPPLY_HEALTH_UNSPEC_FAILURE;
> + else if (ret == 0x0B)
> + val->intval = POWER_SUPPLY_HEALTH_OVERHEAT;
> + else if (ret == 0x0C)
> + val->intval = POWER_SUPPLY_HEALTH_DEAD;
> + else
> + val->intval = POWER_SUPPLY_HEALTH_GOOD;
> + }
> +
> + return 0;
> +}
> +
> +static int bq20z75_get_battery_property(int reg_offset,
> + enum power_supply_property psp,
> + union power_supply_propval *val)
> +{
> + s32 ret;
> +
> + ret = i2c_smbus_read_word_data(bq20z75_device->client,
> + bq20z75_data[reg_offset].addr);
> + if (ret < 0) {
> + dev_err(&bq20z75_device->client->dev,
> + "%s: i2c read for %d failed\n", __func__, reg_offset);
> + return -EINVAL;
> + }
> +
> + if (ret >= bq20z75_data[reg_offset].min_value &&
> + ret <= bq20z75_data[reg_offset].max_value) {
> + val->intval = ret;
> + if (psp == POWER_SUPPLY_PROP_STATUS) {
> + /* mask the upper byte and then find the
> + * actual status */
> + ret &= 0x00FF;
As far as I can see, this masking is a no-op.
-Removed
> + if (ret & BATTERY_CHARGING)
> + val->intval = POWER_SUPPLY_STATUS_CHARGING;
> + else if (ret & BATTERY_FULL_CHARGED)
> + val->intval = POWER_SUPPLY_STATUS_FULL;
> + else if (ret & BATTERY_FULL_DISCHARGED)
> + val->intval = POWER_SUPPLY_STATUS_NOT_CHARGING;
> + else
> + val->intval = POWER_SUPPLY_STATUS_DISCHARGING;
> + }
> + /* bq20z75 provides battery tempreture in 0.1°K
> + * so convert it to °C */
> + else if (psp == POWER_SUPPLY_PROP_TEMP)
> + val->intval = ret - 2731;
> + } else {
> + val->intval = 0;
This should be moved...
> + if (psp == POWER_SUPPLY_PROP_STATUS)
> + val->intval = POWER_SUPPLY_STATUS_UNKNOWN;
... here, with a else.
-Done
> + }
> +
> + return 0;
> +}
> +
> +static int bq20z75_get_battery_capacity(union power_supply_propval *val)
> +{
> + s32 ret;
> +
> + ret = i2c_smbus_read_byte_data(bq20z75_device->client,
> + bq20z75_data[REG_CAPACITY].addr);
> + if (ret < 0) {
> + dev_err(&bq20z75_device->client->dev,
> + "%s: i2c read for %d failed\n", __func__, REG_CAPACITY);
> + return -EINVAL;
> + }
> +
> + /* bq20z75 spec says that this can be >100 %
> + * even if max value is 100 % */
> + val->intval = ((ret >= 100) ? 100 : ret);
Can also be written min(ret, 100).
-Done :)
> +
> + return 0;
> +}
> +
> +static int bq20z75_get_property(struct power_supply *psy,
> + enum power_supply_property psp,
> + union power_supply_propval *val)
> +{
> + u8 count;
For loops like int better.
-Done
> +
> + switch (psp) {
> + case POWER_SUPPLY_PROP_PRESENT:
> + case POWER_SUPPLY_PROP_HEALTH:
> + if (bq20z75_get_battery_presence_and_health(psp, val))
> + return -EINVAL;
You should pass down the exact error value returned by the function,
instead of hardcoding it. Same below.
-Done
> + break;
> +
> + case POWER_SUPPLY_PROP_TECHNOLOGY:
> + val->intval = POWER_SUPPLY_TECHNOLOGY_LION;
> + break;
> +
> + case POWER_SUPPLY_PROP_CAPACITY:
> + if (bq20z75_get_battery_capacity(val))
> + return -EINVAL;
> + break;
> +
> + case POWER_SUPPLY_PROP_STATUS:
> + case POWER_SUPPLY_PROP_CYCLE_COUNT:
> + case POWER_SUPPLY_PROP_VOLTAGE_NOW:
> + case POWER_SUPPLY_PROP_CURRENT_NOW:
> + case POWER_SUPPLY_PROP_TEMP:
> + case POWER_SUPPLY_PROP_TIME_TO_EMPTY_AVG:
> + case POWER_SUPPLY_PROP_TIME_TO_FULL_AVG:
> + case POWER_SUPPLY_PROP_SERIAL_NUMBER:
> + for (count = 0; count < REG_MAX; count++) {
> + if (psp == bq20z75_data[count].psp)
> + break;
> + }
> +
> + if (bq20z75_get_battery_property(count, psp, val))
> + return -EINVAL;
> + break;
Wrong indentation.
-Done
> +
> + default:
> + dev_err(&bq20z75_device->client->dev,
> + "%s: INVALID property\n", __func__);
> + return -EINVAL;
> + }
> +
> + printk(KERN_INFO "%s: property = %d, value = %d\n", __func__,
> + psp, val->intval);
Should be turned into dev_dbg().
-Done
> +
> + return 0;
> +}
> +
> +static int bq20z75_probe(struct i2c_client *client,
> + const struct i2c_device_id *id)
> +{
> + int rc;
> +
> + bq20z75_device = kzalloc(sizeof(*bq20z75_device), GFP_KERNEL);
> + if (!bq20z75_device)
> + return -ENOMEM;
> +
> +memset(bq20z75_device, 0, sizeof(*bq20z75_device));
Wrong indentation, and useless code, as kzalloc did it for you already.
-Removed
> +
> + bq20z75_device->client = client;
> + i2c_set_clientdata(client, bq20z75_device);
> +
> + rc = power_supply_register(&client->dev, &bq20z75_supply);
> + if (rc) {
> + dev_err(&bq20z75_device->client->dev,
> + "%s: Failed to register power supply\n", __func__);
> + kfree(bq20z75_device);
> + return rc;
> + }
> +
> + dev_info(&bq20z75_device->client->dev,
> + "%s: battery driver registered\n", client->name);
What you did here is register a device, not a driver.
-changed to "battery gas gauge device registered"
> +
> + return 0;
> +}
> +
> +static int bq20z75_remove(struct i2c_client *client)
> +{
> + struct bq20z75_device_info *bq20z75_device = i2c_get_clientdata(client);
> +
> + power_supply_unregister(&bq20z75_supply);
> + kfree(bq20z75_device);
> + bq20z75_device = NULL;
> +
> + return 0;
> +}
> +
> +#if defined CONFIG_PM
> +static int bq20z75_suspend(struct i2c_client *client,
> + pm_message_t state)
> +{
> + s32 ret;
> + struct bq20z75_device_info *bq20z75_device = i2c_get_clientdata(client);
You get the data from the client...
> +
> + /* write to manufacture access with sleep command */
(typo: manufacturer)
-Fixed
> + ret = i2c_smbus_write_word_data(bq20z75_device->client,
... just to get the client from the data. Terribly efficient ;)
-Done
> + bq20z75_data[REG_MANUFACTURER_DATA].addr,
> + MANUFACTURER_ACCESS_SLEEP);
> + if (ret < 0) {
> + dev_err(&bq20z75_device->client->dev,
> + "%s: i2c write for %d failed\n",
> + __func__, MANUFACTURER_ACCESS_SLEEP);
> + return -EINVAL;
> + }
> +
> + return 0;
> +}
> +
> +/* any smbus transaction will wake up bq20z75 */
> +static int bq20z75_resume(struct i2c_client *client)
> +{
> + return 0;
> +}
> +#endif
> +
> +static const struct i2c_device_id bq20z75_id[] = {
> + { "bq20z75-battery", 0 },
"-battery" is redundant, just use "bq20z75".
-Done
> + {},
Needless comma.
-Removed
> +};
> +
> +static struct i2c_driver bq20z75_battery_driver = {
> + .probe = bq20z75_probe,
> + .remove = bq20z75_remove,
> +#if defined CONFIG_PM
> + .suspend = bq20z75_suspend,
> + .resume = bq20z75_resume,
> +#endif
> + .id_table = bq20z75_id,
> + .driver = {
> + .name = "bq20z75-battery",
> + },
> +};
> +
> +static int __init bq20z75_battery_init(void)
> +{
> + int ret;
> +
> + ret = i2c_add_driver(&bq20z75_battery_driver);
> + if (ret)
> + dev_err(&bq20z75_device->client->dev,
> + "%s: i2c_add_driver failed\n", __func__);
This is essentially needless. The kernel will log the failure already.
-Fixed up
> +
> + return ret;
> +}
> +module_init(bq20z75_battery_init);
> +
> +static void __exit bq20z75_battery_exit(void)
> +{
> + i2c_del_driver(&bq20z75_battery_driver);
> +}
> +module_exit(bq20z75_battery_exit);
> +
> +MODULE_AUTHOR("NVIDIA Graphics Pvt Ltd");
> +MODULE_DESCRIPTION("BQ20z75 battery monitor driver");
> +MODULE_LICENSE("GPL");
--
Jean Delvare
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