From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lukasz Majewski Date: Tue, 18 Jun 2019 10:06:38 +0200 Subject: [U-Boot] [PATCH 1/2] dm: i2c: Add a flag that need generate stop bit In-Reply-To: <20190617131241.47124-1-chuanhua.han@nxp.com> References: <20190617131241.47124-1-chuanhua.han@nxp.com> Message-ID: <20190618100638.22003bec@jawa> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On Mon, 17 Jun 2019 21:12:40 +0800 Chuanhua Han 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_ADDR_STOP 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 Reviewed-by: Lukasz Majewski > --- > Changes in v4: > - Replace DM_I2C_CHIP_RD_NO_I2C_SETUP_OFFSET with > DM_I2C_CHIP_ADDR_STOP. > > 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_ADDR_STOP)) { > + 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 */ > + DM_I2C_CHIP_ADDR_STOP = 1 << 3, /* Need generate stop bit */ > }; > > 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 at denx.de -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: application/pgp-signature Size: 488 bytes Desc: OpenPGP digital signature URL: