• Eric Miao's avatar
    [ARM] 4304/1: removes the unnecessary bit number from CKENnn_XXXX · 7053acbd
    Eric Miao authored
    This patch removes the unnecessary bit number from CKENnn_XXXX
    definitions for PXA, so that
    
    	CKEN0_PWM0 --> CKEN_PWM0
    	CKEN1_PWM1 --> CKEN_PWM1
    	...
    	CKEN24_CAMERA --> CKEN_CAMERA
    
    The reasons for the change of these defitions are:
    
    1. they do not scale - they are currently valid for pxa2xx, but
    definitely not valid for pxa3xx, e.g., pxa3xx has bit 3 for camera
    instead of bit 24
    
    2. they are unnecessary - the peripheral name within the definition
    has already announced its usage, we don't need those bit numbers
    to know which peripheral we are going to enable/disable clock for
    
    3. they are inconvenient - think about this: a driver programmer
    for pxa has to remember which bit in the CKEN register to turn
    on/off
    
    Another change in the patch is to make the definitions equal to its
    clock bit index, so that
    
       #define CKEN_CAMERA  (24)
    
    instead of
    
       #define CKEN_CAMERA  (1 << 24)
    
    this change, however, will add a run-time bit shift operation in
    pxa_set_cken(), but the benefit of this change is that it scales
    when bit index exceeds 32, e.g., pxa3xx has two registers CKENA
    and CKENB, totally 64 bit for this, suppose CAMERA clock enabling
    bit is CKENB:10, one can simply define CKEN_CAMERA to be (32 + 10)
    and so that pxa_set_cken() need minimum change to adapt to that.
    Signed-off-by: default avatareric miao <eric.y.miao@gmail.com>
    Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
    7053acbd
ohci-pxa27x.c 8.14 KB