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i2c: designware: Add SMBUS quick command support

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The SMBUS emulation code turns an SMBUS quick command into a zero-
length read. This controller can't do zero length accesses, but it
can do quick commands, so reverse the emulation. The alternative
would be to properly implement the SMBUS support but that is a lot
more work, and unnecessary just to get i2cdetect working.

Signed-off-by: Phil Elwell <phil@raspberrypi.com>
This commit is contained in:
Phil Elwell
2020-12-04 15:20:36 +00:00
committed by Dom Cobley
parent 23f115d4a4
commit 7e9fe1d569
2 changed files with 17 additions and 2 deletions
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2
drivers/i2c/busses/i2c-designware-core.h
View File

@@ -123,7 +123,9 @@
#define DW_IC_ERR_TX_ABRT 0x1
#define DW_IC_TAR_SPECIAL BIT(11)
#define DW_IC_TAR_10BITADDR_MASTER BIT(12)
#define DW_IC_TAR_SMBUS_QUICK_CMD BIT(16)
#define DW_IC_COMP_PARAM_1_SPEED_MODE_HIGH (BIT(2) | BIT(3))
#define DW_IC_COMP_PARAM_1_SPEED_MODE_MASK GENMASK(3, 2)

17
drivers/i2c/busses/i2c-designware-master.c
View File

@@ -265,6 +265,10 @@ static void i2c_dw_xfer_init(struct dw_i2c_dev *dev)
ic_tar = DW_IC_TAR_10BITADDR_MASTER;
}
/* Convert a zero-length read into an SMBUS quick command */
if (!msgs[dev->msg_write_idx].len)
ic_tar = DW_IC_TAR_SPECIAL | DW_IC_TAR_SMBUS_QUICK_CMD;
regmap_update_bits(dev->map, DW_IC_CON, DW_IC_CON_10BITADDR_MASTER,
ic_con);
@@ -475,6 +479,14 @@ i2c_dw_xfer_msg(struct dw_i2c_dev *dev)
regmap_read(dev->map, DW_IC_RXFLR, &flr);
rx_limit = dev->rx_fifo_depth - flr;
/* Handle SMBUS quick commands */
if (!buf_len) {
if (msgs[dev->msg_write_idx].flags & I2C_M_RD)
regmap_write(dev->map, DW_IC_DATA_CMD, 0x300);
else
regmap_write(dev->map, DW_IC_DATA_CMD, 0x200);
}
while (buf_len > 0 && tx_limit > 0 && rx_limit > 0) {
u32 cmd = 0;
@@ -912,14 +924,15 @@ static const struct i2c_algorithm i2c_dw_algo = {
};
static const struct i2c_adapter_quirks i2c_dw_quirks = {
.flags = I2C_AQ_NO_ZERO_LEN,
.flags = 0,
};
void i2c_dw_configure_master(struct dw_i2c_dev *dev)
{
struct i2c_timings *t = &dev->timings;
dev->functionality = I2C_FUNC_10BIT_ADDR | DW_IC_DEFAULT_FUNCTIONALITY;
dev->functionality = I2C_FUNC_10BIT_ADDR | I2C_FUNC_SMBUS_QUICK |
DW_IC_DEFAULT_FUNCTIONALITY;
dev->master_cfg = DW_IC_CON_MASTER | DW_IC_CON_SLAVE_DISABLE |
DW_IC_CON_RESTART_EN;