diff options
| author | Zev Weiss <zev@bewilderbeest.net> | 2021-05-06 15:54:19 -0500 |
|---|---|---|
| committer | Wolfram Sang <wsa@kernel.org> | 2021-05-27 21:44:19 +0200 |
| commit | 3fb2e2aeafb2d28e49d9c069ac392dabe595b1ae (patch) | |
| tree | 94997a1f23c1333e776fdfc5de2b3319967c16f6 /drivers/i2c | |
| parent | c8062d11e20c218b310145bc918e116423fb1e83 (diff) | |
i2c: aspeed: disable additional device addresses on ast2[56]xx
The ast25xx and ast26xx have, respectively, two and three configurable
slave device addresses to the ast24xx's one. We only support using
one at a time, but the others may come up in an indeterminate state
depending on hardware/bootloader behavior, so we need to make sure we
disable them so as to avoid ending up with phantom devices on the bus.
Signed-off-by: Zev Weiss <zev@bewilderbeest.net>
Reviewed-by: Brendan Higgins <brendanhiggins@google.com>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Tested-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
Diffstat (limited to 'drivers/i2c')
| -rw-r--r-- | drivers/i2c/busses/i2c-aspeed.c | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/drivers/i2c/busses/i2c-aspeed.c b/drivers/i2c/busses/i2c-aspeed.c index 724bf30600d6..67e8b97c0c95 100644 --- a/drivers/i2c/busses/i2c-aspeed.c +++ b/drivers/i2c/busses/i2c-aspeed.c @@ -727,10 +727,14 @@ static void __aspeed_i2c_reg_slave(struct aspeed_i2c_bus *bus, u16 slave_addr) { u32 addr_reg_val, func_ctrl_reg_val; - /* Set slave addr. */ - addr_reg_val = readl(bus->base + ASPEED_I2C_DEV_ADDR_REG); - addr_reg_val &= ~ASPEED_I2CD_DEV_ADDR_MASK; - addr_reg_val |= slave_addr & ASPEED_I2CD_DEV_ADDR_MASK; + /* + * Set slave addr. Reserved bits can all safely be written with zeros + * on all of ast2[456]00, so zero everything else to ensure we only + * enable a single slave address (ast2500 has two, ast2600 has three, + * the enable bits for which are also in this register) so that we don't + * end up with additional phantom devices responding on the bus. + */ + addr_reg_val = slave_addr & ASPEED_I2CD_DEV_ADDR_MASK; writel(addr_reg_val, bus->base + ASPEED_I2C_DEV_ADDR_REG); /* Turn on slave mode. */ |