On Tue, 4 Jun 2019 06:48:59 +0000 Chuanhua Han chuanhua.han@nxp.com wrote:
-----Original Message----- From: Lukasz Majewski lukma@denx.de Sent: 2019年6月4日 14:46 To: Chuanhua Han chuanhua.han@nxp.com Cc: hs@denx.de; u-boot@lists.denx.de; Biwen Li biwen.li@nxp.com Subject: Re: [EXT] Re: [U-Boot] [PATCH 1/2] dm: i2c: Add a flag that not call i2c_setup_offset
On Tue, 4 Jun 2019 02:20:49 +0000 Chuanhua Han chuanhua.han@nxp.com wrote:
-----Original Message----- From: Lukasz Majewski lukma@denx.de Sent: 2019年6月4日 6:08 To: Chuanhua Han chuanhua.han@nxp.com Cc: hs@denx.de; u-boot@lists.denx.de; Biwen Li biwen.li@nxp.com Subject: [EXT] Re: [U-Boot] [PATCH 1/2] dm: i2c: Add a flag that not call i2c_setup_offset
On Thu, 30 May 2019 18:31:48 +0800 Chuanhua Han chuanhua.han@nxp.com wrote:
Usually the i2c bus needs to write the address of the register before reading the internal register data of the device (ignoring the transmission of the slave address).
Generally, the stop signal is not needed before the register is read, but there is a special chip that needs this stop signal (such as pcf2127). However, in the current i2c general code, the dm_i2c_read api encapsulates two messages, the first time is to set the register address message, the second time is a message to read the register data, so that no stop signal is generated.
This patch uses the DM_I2C_CHIP_RD_NO_I2C_SETUP_OFFSET flag for specific i2c chips, so if the i2c slave requires a stop signal, chips driver can set this flag, then call the dm_i2c_write to set the register address (a stop signal is generated after this API call), then call dm_i2c_read to read the register data.
Signed-off-by: Chuanhua Han chuanhua.han@nxp.com
Changes in v3:
- Use the new flag DM_I2C_CHIP_RD_NO_I2C_SETUP_OFFSET
Changes in v2: - Split the original patch into 3 patches - Add detailed description information for each patch
drivers/i2c/i2c-uclass.c | 6 ++++-- include/i2c.h | 1 + 2 files changed, 5 insertions(+), 2 deletions(-)
diff --git a/drivers/i2c/i2c-uclass.c b/drivers/i2c/i2c-uclass.c index e47abf1833..9804b5e8c7 100644 --- a/drivers/i2c/i2c-uclass.c +++ b/drivers/i2c/i2c-uclass.c @@ -135,8 +135,10 @@ int dm_i2c_read(struct udevice *dev, uint offset, uint8_t *buffer, int len) if (chip->flags & DM_I2C_CHIP_RD_ADDRESS) return i2c_read_bytewise(dev, offset, buffer, len); ptr = msg;
- if (!i2c_setup_offset(chip, offset, offset_buf, ptr))
ptr++;
- if (!(chip->flags &
DM_I2C_CHIP_RD_NO_I2C_SETUP_OFFSET)) {
if (!i2c_setup_offset(chip, offset,offset_buf, ptr))
ptr++;}
if (len) { ptr->addr = chip->chip_addr;
diff --git a/include/i2c.h b/include/i2c.h index a5c760c711..3123cbf280 100644 --- a/include/i2c.h +++ b/include/i2c.h @@ -28,6 +28,7 @@ enum dm_i2c_chip_flags { DM_I2C_CHIP_10BIT = 1 << 0, /* Use 10-bit addressing */ DM_I2C_CHIP_RD_ADDRESS = 1 << 1, /* Send address for each read byte */ DM_I2C_CHIP_WR_ADDRESS = 1 << 2, /* Send address for each write byte */
Aren't those two above flags describe exactly what you need? They send address for each read/written byte. (or do you need to send more than a single byte)?
This is not what I need. I need to generate a stop signal after setting the register address,
Please correct me if I'm wrong, but the above flag says that you need to send the I2C stop after you send one byte?
Would it be possible to send address with I2C stop and then read data (single byte) with I2C stop?
so I need the following flag.
DM_I2C_CHIP_RD_NO_I2C_SETUP_OFFSET = 1 << 3,
I do find this name as a bit misleading - is the RD_NO_I2C_SETUP_OFFSET name reflecting the purpose (to send I2C stop after sending address)?
The purpose is to send a stop signal after setting the slave register address.
What I'm trying to point out is that the above description doesn't match the flag name. Maybe there is a better, more descriptive name?
Also - what is byte length of send address to this device? One byte ?
Maybe there would be a better name?
/* No i2c_setup_offset*/ };struct udevice;
Best regards,
Lukasz Majewski
--
DENX Software Engineering GmbH, Managing Director: Wolfgang Denk HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email: lukma@denx.de
Best regards,
Lukasz Majewski
--
DENX Software Engineering GmbH, Managing Director: Wolfgang Denk HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email: lukma@denx.de
Best regards,
Lukasz Majewski
--
DENX Software Engineering GmbH, Managing Director: Wolfgang Denk HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email: lukma@denx.de