From 8e8782c71595a5ad29e234ce6b3d2fce787fb07a Mon Sep 17 00:00:00 2001 From: Kaushal Butala Date: Fri, 4 Apr 2014 14:56:10 +0200 Subject: [PATCH] i2c: imx: add SMBus block read support The smbus block read is not currently supported for imx i2c devices. This patchset adds the support to imx i2c bus so that blocks of data can be read using SMbus block reads.(using i2c_smbus_read_block_data() function from the i2c_core.c.). Tested with 3.10.9 kernel. Reviewed-by: Shawn Guo Signed-off-by: Kaushal Butala Signed-off-by: Wolfram Sang --- drivers/i2c/busses/i2c-imx.c | 31 ++++++++++++++++++++++++++++--- 1 file changed, 28 insertions(+), 3 deletions(-) diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c index db895fb22e65..886217f1ba61 100644 --- a/drivers/i2c/busses/i2c-imx.c +++ b/drivers/i2c/busses/i2c-imx.c @@ -462,6 +462,7 @@ static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs) { int i, result; unsigned int temp; + int block_data = msgs->flags & I2C_M_RECV_LEN; dev_dbg(&i2c_imx->adapter.dev, "<%s> write slave address: addr=0x%x\n", @@ -481,7 +482,12 @@ static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs) /* setup bus to read data */ temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR); temp &= ~I2CR_MTX; - if (msgs->len - 1) + + /* + * Reset the I2CR_TXAK flag initially for SMBus block read since the + * length is unknown + */ + if ((msgs->len - 1) || block_data) temp &= ~I2CR_TXAK; imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR); imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR); /* dummy read */ @@ -490,9 +496,24 @@ static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs) /* read data */ for (i = 0; i < msgs->len; i++) { + u8 len = 0; result = i2c_imx_trx_complete(i2c_imx); if (result) return result; + /* + * First byte is the length of remaining packet + * in the SMBus block data read. Add it to + * msgs->len. + */ + if ((!i) && block_data) { + len = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR); + if ((len == 0) || (len > I2C_SMBUS_BLOCK_MAX)) + return -EPROTO; + dev_dbg(&i2c_imx->adapter.dev, + "<%s> read length: 0x%X\n", + __func__, len); + msgs->len += len; + } if (i == (msgs->len - 1)) { /* It must generate STOP before read I2DR to prevent controller from generating another clock cycle */ @@ -510,7 +531,10 @@ static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs) temp |= I2CR_TXAK; imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR); } - msgs->buf[i] = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR); + if ((!i) && block_data) + msgs->buf[0] = len; + else + msgs->buf[i] = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR); dev_dbg(&i2c_imx->adapter.dev, "<%s> read byte: B%d=0x%X\n", __func__, i, msgs->buf[i]); @@ -583,7 +607,8 @@ fail0: static u32 i2c_imx_func(struct i2c_adapter *adapter) { - return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL; + return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL + | I2C_FUNC_SMBUS_READ_BLOCK_DATA; } static struct i2c_algorithm i2c_imx_algo = { -- 2.39.5