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i2c: bcm2835: Set clock-stretch timeout to 35ms #3068

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Jul 12, 2019
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i2c: bcm2835: Set clock-stretch timeout to 35ms #3068

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12 changes: 12 additions & 0 deletions drivers/i2c/busses/i2c-bcm2835.c
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Original file line number Diff line number Diff line change
Expand Up @@ -194,6 +194,7 @@ static int clk_bcm2835_i2c_set_rate(struct clk_hw *hw, unsigned long rate,
{
struct clk_bcm2835_i2c *div = to_clk_bcm2835_i2c(hw);
u32 redl, fedl;
u32 clk_tout;
u32 divider = clk_bcm2835_i2c_calc_divider(rate, parent_rate);

if (divider == -EINVAL)
Expand All @@ -217,6 +218,17 @@ static int clk_bcm2835_i2c_set_rate(struct clk_hw *hw, unsigned long rate,
bcm2835_i2c_writel(div->i2c_dev, BCM2835_I2C_DEL,
(fedl << BCM2835_I2C_FEDL_SHIFT) |
(redl << BCM2835_I2C_REDL_SHIFT));

/*
* Set the clock stretch timeout to the SMBUs-recommended 35ms.
*/
if (rate > 0xffff*1000/35)
clk_tout = 0xffff;
else
clk_tout = 35*rate/1000;

bcm2835_i2c_writel(div->i2c_dev, BCM2835_I2C_CLKT, clk_tout);

return 0;
}

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