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| author | Arseny Solokha <asolokha@kb.kras.ru> | 2017-12-07 17:20:00 +0700 |
|---|---|---|
| committer | Wolfram Sang <wsa@the-dreams.de> | 2018-01-15 19:13:06 +0100 |
| commit | 6d106139191e58b9f4ef126cfc1e3c26c0d6702e (patch) | |
| tree | e72c8ea76087ae8cb8ed739865d07e167ab05b5d /drivers/i2c | |
| parent | aad550f93fbc28d562a624700f9c12c9b9055a5e (diff) | |
| download | linux-6d106139191e58b9f4ef126cfc1e3c26c0d6702e.tar.gz linux-6d106139191e58b9f4ef126cfc1e3c26c0d6702e.tar.bz2 linux-6d106139191e58b9f4ef126cfc1e3c26c0d6702e.zip | |
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>
Diffstat (limited to 'drivers/i2c')
| -rw-r--r-- | drivers/i2c/busses/i2c-mpc.c | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/drivers/i2c/busses/i2c-mpc.c b/drivers/i2c/busses/i2c-mpc.c index 950a9d74f54d..6ad87555f71e 100644 --- a/drivers/i2c/busses/i2c-mpc.c +++ b/drivers/i2c/busses/i2c-mpc.c @@ -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", |