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i2c: aspeed: disable additional device addresses on ast2[56]xx

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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>
This commit is contained in:
Zev Weiss 2021-05-06 15:54:19 -05:00 • committed by Wolfram Sang
parent c8062d11e2
commit 3fb2e2aeaf
1 changed files with 8 additions and 4 deletions
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12
drivers/i2c/busses/i2c-aspeed.c
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@ -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. */