iris

iris Git Source Tree

1	cclk: cpu clock. Fastest clock in the system.
2	hclk: high-speed peripheral bus clock.
3	pclk: peripheral bus clock.
4	mclk: memory clock, for emc.
5	ldclk: lcd device clock.
6	lpclk: lcd pixel clock.
7	cim_mclk: clock output for cim.
8	cim_pclk: clock input for cim.
9	i2sclk: codec clock.
10	mscclk: msc clock.
11	ssiclk: ssi clock.
12	exclk: 12MHz clock output, used by uart, i2c, ssi, tcu, usb2.0-phy.
13	rtclk: 32768Hz clock input for rtc.
14
15	cclk: 252M
16	hclk: 84M
17	pclk: 84M
18	mclk: 84M
19	ldclk: 84M; must not be larger than 150M
20	lpclk: 25295340 (70Hz screen refresh)
21	cim_mclk: not used.
22	cim_pclk: not used.
23	i2sclk: must be 12M
24	mscclk: must not be larger than 400k during init; not larger than 25M later.
25	ssiclk: not used.
26	exclk: 12M, not adjustable.
27	rtclk: 32768, not adjustable.
28
29	usb clock, for host and device, must be 48M.
30
31	restrictions:
32	- cclk must be i*hclk
33	- i must not be 24 or 32
34	- hclk = mclk or hclk = 2*mclk
35	- mclk = k*pclk
36
37	so:
38	- pclk is set
39	- mclk = k*pclk
40	- hclk = lmclk = lk*pclk; l = 1 or 2
41	- cclk = ihclk = ilkpclk; i != 24 or 32
42
43	In the code:
44	m = 42
45	n = 2
46	no = 1
47	So clkout = 12M * 21 = 252M; this is the pll clock frequency.
48

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