Commit | Line | Data |
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13082398 MV |
1 | /* |
2 | * Copyright 2012 DENX Software Engineering, GmbH | |
3 | * | |
4 | * Pulled from code: | |
5 | * Portions copyright (C) 2003 Russell King, PXA MMCI Driver | |
6 | * Portions copyright (C) 2004-2005 Pierre Ossman, W83L51xD SD/MMC driver | |
7 | * | |
8 | * Copyright 2008 Embedded Alley Solutions, Inc. | |
9 | * Copyright 2009-2011 Freescale Semiconductor, Inc. | |
10 | * | |
11 | * The code contained herein is licensed under the GNU General Public | |
12 | * License. You may obtain a copy of the GNU General Public License | |
13 | * Version 2 or later at the following locations: | |
14 | * | |
15 | * http://www.opensource.org/licenses/gpl-license.html | |
16 | * http://www.gnu.org/copyleft/gpl.html | |
17 | */ | |
18 | ||
19 | #include <linux/kernel.h> | |
20 | #include <linux/init.h> | |
21 | #include <linux/clk.h> | |
22 | #include <linux/module.h> | |
23 | #include <linux/device.h> | |
24 | #include <linux/io.h> | |
25 | #include <linux/spi/mxs-spi.h> | |
26 | ||
27 | void mxs_ssp_set_clk_rate(struct mxs_ssp *ssp, unsigned int rate) | |
28 | { | |
29 | unsigned int ssp_clk, ssp_sck; | |
30 | u32 clock_divide, clock_rate; | |
31 | u32 val; | |
32 | ||
33 | ssp_clk = clk_get_rate(ssp->clk); | |
34 | ||
35 | for (clock_divide = 2; clock_divide <= 254; clock_divide += 2) { | |
36 | clock_rate = DIV_ROUND_UP(ssp_clk, rate * clock_divide); | |
37 | clock_rate = (clock_rate > 0) ? clock_rate - 1 : 0; | |
38 | if (clock_rate <= 255) | |
39 | break; | |
40 | } | |
41 | ||
42 | if (clock_divide > 254) { | |
43 | dev_err(ssp->dev, | |
44 | "%s: cannot set clock to %d\n", __func__, rate); | |
45 | return; | |
46 | } | |
47 | ||
48 | ssp_sck = ssp_clk / clock_divide / (1 + clock_rate); | |
49 | ||
50 | val = readl(ssp->base + HW_SSP_TIMING(ssp)); | |
51 | val &= ~(BM_SSP_TIMING_CLOCK_DIVIDE | BM_SSP_TIMING_CLOCK_RATE); | |
52 | val |= BF_SSP(clock_divide, TIMING_CLOCK_DIVIDE); | |
53 | val |= BF_SSP(clock_rate, TIMING_CLOCK_RATE); | |
54 | writel(val, ssp->base + HW_SSP_TIMING(ssp)); | |
55 | ||
56 | ssp->clk_rate = ssp_sck; | |
57 | ||
58 | dev_dbg(ssp->dev, | |
59 | "%s: clock_divide %d, clock_rate %d, ssp_clk %d, rate_actual %d, rate_requested %d\n", | |
60 | __func__, clock_divide, clock_rate, ssp_clk, ssp_sck, rate); | |
61 | } | |
62 | EXPORT_SYMBOL_GPL(mxs_ssp_set_clk_rate); |