On Mon, 5 Dec 2011, Paul Walmsley wrote:
For example, here's a trivial implementation for rate recalculation for a integer divider clock node (that can't be handled with a right shift):
s64 div(struct clk *clk, u32 div) { if (clk->flags & CLK_PARENT_RATE_MAX_U32) return ((u32)(clk->parent->rate & 0xffffffff)) / div;
clk->rate = clk->parent->rate; do_div(clk->rate, div); return clk->rate; }
(removing some useless cruft from the above function, for clarity's sake)
s64 div(struct clk *clk, u32 div) { s64 r;
if (clk->flags & CLK_PARENT_RATE_MAX_U32) return ((u32)clk->parent->rate) / div;
r = clk->parent->rate; do_div(r, div); return r; }
00000000 <div>: 0: e92d4010 push {r4, lr} 4: e1a04001 mov r4, r1 8: e5d03010 ldrb r3, [r0, #16] c: e3130001 tst r3, #1 10: 1a000005 bne 2c <div+0x2c>
14: e5903000 ldr r3, [r0] 18: e1c300d8 ldrd r0, [r3, #8] 1c: ebfffffe bl 0 <__do_div64> 20: e1a00002 mov r0, r2 24: e1a01003 mov r1, r3 28: e8bd8010 pop {r4, pc}
2c: e5900000 ldr r0, [r0] 30: e5900008 ldr r0, [r0, #8] 34: ebfffffe bl 0 <__aeabi_uidiv> 38: e3a01000 mov r1, #0 3c: e8bd8010 pop {r4, pc}
- Paul