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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 000000000000..9aef710e9a4b --- /dev/null +++ b/Documentation/sh/clk.txt | |||
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1 | Clock framework on SuperH architecture | ||
2 | |||
3 | The framework on SH extends existing API by the function clk_set_rate_ex, | ||
4 | which prototype is as follows: | ||
5 | |||
6 | clk_set_rate_ex (struct clk *clk, unsigned long rate, int algo_id) | ||
7 | |||
8 | The algo_id parameter is used to specify algorithm used to recalculate clocks, | ||
9 | adjanced to clock, specified as first argument. It is assumed that algo_id==0 | ||
10 | means no changes to adjanced clock | ||
11 | |||
12 | Internally, the clk_set_rate_ex forwards request to clk->ops->set_rate method, | ||
13 | if it is present in ops structure. The method should set the clock rate and adjust | ||
14 | all needed clocks according to the passed algo_id. | ||
15 | Exact values for algo_id are machine-dependend. For the sh7722, the following | ||
16 | values are defined: | ||
17 | |||
18 | NO_CHANGE = 0, | ||
19 | IUS_N1_N1, /* I:U = N:1, U:Sh = N:1 */ | ||
20 | IUS_322, /* I:U:Sh = 3:2:2 */ | ||
21 | IUS_522, /* I:U:Sh = 5:2:2 */ | ||
22 | IUS_N11, /* I:U:Sh = N:1:1 */ | ||
23 | SB_N1, /* Sh:B = N:1 */ | ||
24 | SB3_N1, /* Sh:B3 = N:1 */ | ||
25 | SB3_32, /* Sh:B3 = 3:2 */ | ||
26 | SB3_43, /* Sh:B3 = 4:3 */ | ||
27 | SB3_54, /* Sh:B3 = 5:4 */ | ||
28 | BP_N1, /* B:P = N:1 */ | ||
29 | IP_N1 /* I:P = N:1 */ | ||
30 | |||
31 | Each of these constants means relation between clocks that can be set via the FRQCR | ||
32 | register | ||