Re: [PATCH] i2c: add pmic_reg_read() for PBL use

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

On 02.01.24 10:11, Sascha Hauer wrote:
> On Tue, Dec 19, 2023 at 05:21:35PM +0100, Ahmad Fatoum wrote:
>> Hello Bastian,
>>
>> On 19.12.23 17:11, Bastian Krause wrote:
>>> Add a common PMIC read function to PBL which allows easy porting of
>>> U-Boot's pmic_reg_read() in lowlevel board code.
>>>
>>> Signed-off-by: Bastian Krause <bst@pengutronix.de>
>>> ---
>>>  include/pbl/pmic.h | 21 +++++++++++++++++++++
>>>  1 file changed, 21 insertions(+)
>>>
>>> diff --git a/include/pbl/pmic.h b/include/pbl/pmic.h
>>> index 0f882c5649d..bd0583370ec 100644
>>> --- a/include/pbl/pmic.h
>>> +++ b/include/pbl/pmic.h
>>> @@ -9,6 +9,27 @@ struct pmic_config {
>>>  	u8 val;
>>>  };
>>>  
>>> +static void pmic_reg_read(struct pbl_i2c *i2c, int addr, u8 reg, void *buf)
>>
>> This should be static inline to avoid warnings for boards that don't use it.
>>
>>> +{
>>> +	int ret;
>>> +	struct i2c_msg msg[] = {
>>> +		{
>>> +			.addr = addr,
>>> +			.buf = &reg,
>>> +			.len = 1,
>>> +		}, {
>>> +			.addr = addr,
>>> +			.flags = I2C_M_RD,
>>> +			.buf = buf,
>>
>> U-Boot has buf of type u32 *. In your barebox implementation, only the
>> first byte is written, so this leaves 3 bytes potentially uninitialized.
>>
>> You likely want to change void *buf to u32 *val and then
>>
>>   u8 buf[1];
>>   /* i2c_xfer... */
>>   *val = buf[0];
> 
> When *buf is assumed to be a single byte only anyway then we can change
> its type to u8 *

For ease of porting from U-Boot board code, we should just keep the same prototype.

Cheers,
Ahmad

> 
> Sascha
> 
>>
>>> +			.len = 1,
>>> +		},
>>> +	};
>>> +
>>> +	ret = pbl_i2c_xfer(i2c, msg, ARRAY_SIZE(msg));
>>> +	if (ret != ARRAY_SIZE(msg))
>>> +		pr_err("Failed to read from pmic@%x: %d\n", addr, ret);
>>> +}
>>
>> Cheers,
>> Ahmad
>>
>>> +
>>>  static void pmic_reg_write(struct pbl_i2c *i2c, int addr, u8 reg, u8 val)
>>>  {
>>>  	int ret;
>>
>> -- 
>> Pengutronix e.K.                           |                             |
>> Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
>> 31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
>> Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |
>>
>>
>>
> 

-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |