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Diffstat (limited to 'Documentation/sh/clk.txt')
| -rw-r--r-- | Documentation/sh/clk.txt | 32 |
1 files changed, 32 insertions, 0 deletions
diff --git a/Documentation/sh/clk.txt b/Documentation/sh/clk.txt new file mode 100644 index 00000000000..9aef710e9a4 --- /dev/null +++ b/Documentation/sh/clk.txt @@ -0,0 +1,32 @@ +Clock framework on SuperH architecture + +The framework on SH extends existing API by the function clk_set_rate_ex, +which prototype is as follows: + + clk_set_rate_ex (struct clk *clk, unsigned long rate, int algo_id) + +The algo_id parameter is used to specify algorithm used to recalculate clocks, +adjanced to clock, specified as first argument. It is assumed that algo_id==0 +means no changes to adjanced clock + +Internally, the clk_set_rate_ex forwards request to clk->ops->set_rate method, +if it is present in ops structure. The method should set the clock rate and adjust +all needed clocks according to the passed algo_id. +Exact values for algo_id are machine-dependend. For the sh7722, the following +values are defined: + + NO_CHANGE = 0, + IUS_N1_N1, /* I:U = N:1, U:Sh = N:1 */ + IUS_322, /* I:U:Sh = 3:2:2 */ + IUS_522, /* I:U:Sh = 5:2:2 */ + IUS_N11, /* I:U:Sh = N:1:1 */ + SB_N1, /* Sh:B = N:1 */ + SB3_N1, /* Sh:B3 = N:1 */ + SB3_32, /* Sh:B3 = 3:2 */ + SB3_43, /* Sh:B3 = 4:3 */ + SB3_54, /* Sh:B3 = 5:4 */ + BP_N1, /* B:P = N:1 */ + IP_N1 /* I:P = N:1 */ + +Each of these constants means relation between clocks that can be set via the FRQCR +register |