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i2c: mpc: get MPC8xxx I2C clock prescaler before using it in calculations 

Obtaining the actual I2C clock prescaler value in mpc_i2c_setup_8xxx() only
happens when the clock parameter is set to something other than
MPC_I2C_CLOCK_LEGACY. When the clock parameter is exactly
MPC_I2C_CLOCK_LEGACY, the prescaler parameter is used in arithmetic
division as provided by the caller, resulting in a division by zero
for the majority of processors supported by the module.

Avoid division by zero by obtaining the actual I2C clock prescaler
in mpc_i2c_setup_8xxx() unconditionally regardless of the passed clock
value.

Signed-off-by: Arseny Solokha <asolokha@kb.kras.ru>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
This commit is contained in:
Arseny Solokha 2017-12-07 17:20:00 +07:00 committed by Wolfram Sang
parent aad550f93f
commit 6d10613919
1 changed files with 6 additions and 6 deletions
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12
drivers/i2c/busses/i2c-mpc.c
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@ -382,18 +382,18 @@ static int mpc_i2c_get_fdr_8xxx(struct device_node *node, u32 clock,
u32 divider;
int i;
if (clock == MPC_I2C_CLOCK_LEGACY) {
/* see below - default fdr = 0x1031 -> div = 16 * 3072 */
*real_clk = fsl_get_sys_freq() / prescaler / (16 * 3072);
return -EINVAL;
}
/* Determine proper divider value */
if (of_device_is_compatible(node, "fsl,mpc8544-i2c"))
prescaler = mpc_i2c_get_sec_cfg_8xxx() ? 3 : 2;
if (!prescaler)
prescaler = mpc_i2c_get_prescaler_8xxx();
if (clock == MPC_I2C_CLOCK_LEGACY) {
/* see below - default fdr = 0x1031 -> div = 16 * 3072 */
*real_clk = fsl_get_sys_freq() / prescaler / (16 * 3072);
return -EINVAL;
}
divider = fsl_get_sys_freq() / clock / prescaler;
pr_debug("I2C: src_clock=%d clock=%d divider=%d\n",