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i2c: designware: use casting of u64 in clock multiplication to avoid overflow 

In functions i2c_dw_scl_lcnt() and i2c_dw_scl_hcnt() may have overflow
by depending on the values of the given parameters including the ic_clk.
For example in our use case where ic_clk is larger than one million,
multiplication of ic_clk * 4700 will result in 32 bit overflow.

Add cast of u64 to the calculation to avoid multiplication overflow, and
use the corresponding define for divide.

Fixes: 2373f6b974 ("i2c-designware: split of i2c-designware.c into core and bus specific parts")
Signed-off-by: Lareine Khawaly <lareine@amazon.com>
Signed-off-by: Hanna Hawa <hhhawa@amazon.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
This commit is contained in:
Lareine Khawaly 2022-12-21 19:59:00 +00:00 committed by Wolfram Sang
parent b7bfaa761d
commit c8c37bc514
1 changed files with 6 additions and 3 deletions
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9
drivers/i2c/busses/i2c-designware-common.c
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@ -351,7 +351,8 @@ u32 i2c_dw_scl_hcnt(u32 ic_clk, u32 tSYMBOL, u32 tf, int cond, int offset)
*
* If your hardware is free from tHD;STA issue, try this one.
*/
return DIV_ROUND_CLOSEST(ic_clk * tSYMBOL, MICRO) - 8 + offset;
return DIV_ROUND_CLOSEST_ULL((u64)ic_clk * tSYMBOL, MICRO) -
8 + offset;
else
/*
* Conditional expression:
@ -367,7 +368,8 @@ u32 i2c_dw_scl_hcnt(u32 ic_clk, u32 tSYMBOL, u32 tf, int cond, int offset)
* The reason why we need to take into account "tf" here,
* is the same as described in i2c_dw_scl_lcnt().
*/
return DIV_ROUND_CLOSEST(ic_clk * (tSYMBOL + tf), MICRO) - 3 + offset;
return DIV_ROUND_CLOSEST_ULL((u64)ic_clk * (tSYMBOL + tf), MICRO) -
3 + offset;
}
u32 i2c_dw_scl_lcnt(u32 ic_clk, u32 tLOW, u32 tf, int offset)
@ -383,7 +385,8 @@ u32 i2c_dw_scl_lcnt(u32 ic_clk, u32 tLOW, u32 tf, int offset)
* account the fall time of SCL signal (tf). Default tf value
* should be 0.3 us, for safety.
*/
return DIV_ROUND_CLOSEST(ic_clk * (tLOW + tf), MICRO) - 1 + offset;
return DIV_ROUND_CLOSEST_ULL((u64)ic_clk * (tLOW + tf), MICRO) -
1 + offset;
}
int i2c_dw_set_sda_hold(struct dw_i2c_dev *dev)