Commit | Line | Data |
---|---|---|
8060ef4d SN |
1 | /* |
2 | * AEMIF support for DaVinci SoCs | |
3 | * | |
4 | * Copyright (C) 2010 Texas Instruments Incorporated. http://www.ti.com/ | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify | |
7 | * it under the terms of the GNU General Public License version 2 as | |
8 | * published by the Free Software Foundation. | |
9 | */ | |
10 | ||
11 | #include <linux/kernel.h> | |
12 | #include <linux/io.h> | |
13 | #include <linux/err.h> | |
14 | #include <linux/clk.h> | |
15 | #include <linux/module.h> | |
16 | #include <linux/time.h> | |
17 | ||
18 | #include <mach/aemif.h> | |
19 | ||
20 | /* Timing value configuration */ | |
21 | ||
22 | #define TA(x) ((x) << 2) | |
23 | #define RHOLD(x) ((x) << 4) | |
24 | #define RSTROBE(x) ((x) << 7) | |
25 | #define RSETUP(x) ((x) << 13) | |
26 | #define WHOLD(x) ((x) << 17) | |
27 | #define WSTROBE(x) ((x) << 20) | |
28 | #define WSETUP(x) ((x) << 26) | |
29 | ||
30 | #define TA_MAX 0x3 | |
31 | #define RHOLD_MAX 0x7 | |
32 | #define RSTROBE_MAX 0x3f | |
33 | #define RSETUP_MAX 0xf | |
34 | #define WHOLD_MAX 0x7 | |
35 | #define WSTROBE_MAX 0x3f | |
36 | #define WSETUP_MAX 0xf | |
37 | ||
38 | #define TIMING_MASK (TA(TA_MAX) | \ | |
39 | RHOLD(RHOLD_MAX) | \ | |
40 | RSTROBE(RSTROBE_MAX) | \ | |
41 | RSETUP(RSETUP_MAX) | \ | |
42 | WHOLD(WHOLD_MAX) | \ | |
43 | WSTROBE(WSTROBE_MAX) | \ | |
44 | WSETUP(WSETUP_MAX)) | |
45 | ||
46 | /* | |
47 | * aemif_calc_rate - calculate timing data. | |
48 | * @wanted: The cycle time needed in nanoseconds. | |
49 | * @clk: The input clock rate in kHz. | |
50 | * @max: The maximum divider value that can be programmed. | |
51 | * | |
52 | * On success, returns the calculated timing value minus 1 for easy | |
53 | * programming into AEMIF timing registers, else negative errno. | |
54 | */ | |
55 | static int aemif_calc_rate(int wanted, unsigned long clk, int max) | |
56 | { | |
57 | int result; | |
58 | ||
59 | result = DIV_ROUND_UP((wanted * clk), NSEC_PER_MSEC) - 1; | |
60 | ||
61 | pr_debug("%s: result %d from %ld, %d\n", __func__, result, clk, wanted); | |
62 | ||
63 | /* It is generally OK to have a more relaxed timing than requested... */ | |
64 | if (result < 0) | |
65 | result = 0; | |
66 | ||
67 | /* ... But configuring tighter timings is not an option. */ | |
68 | else if (result > max) | |
69 | result = -EINVAL; | |
70 | ||
71 | return result; | |
72 | } | |
73 | ||
74 | /** | |
75 | * davinci_aemif_setup_timing - setup timing values for a given AEMIF interface | |
76 | * @t: timing values to be progammed | |
77 | * @base: The virtual base address of the AEMIF interface | |
78 | * @cs: chip-select to program the timing values for | |
79 | * | |
80 | * This function programs the given timing values (in real clock) into the | |
81 | * AEMIF registers taking the AEMIF clock into account. | |
82 | * | |
83 | * This function does not use any locking while programming the AEMIF | |
84 | * because it is expected that there is only one user of a given | |
85 | * chip-select. | |
86 | * | |
87 | * Returns 0 on success, else negative errno. | |
88 | */ | |
89 | int davinci_aemif_setup_timing(struct davinci_aemif_timing *t, | |
90 | void __iomem *base, unsigned cs) | |
91 | { | |
92 | unsigned set, val; | |
12cdd3d7 | 93 | int ta, rhold, rstrobe, rsetup, whold, wstrobe, wsetup; |
8060ef4d SN |
94 | unsigned offset = A1CR_OFFSET + cs * 4; |
95 | struct clk *aemif_clk; | |
96 | unsigned long clkrate; | |
97 | ||
98 | if (!t) | |
99 | return 0; /* Nothing to do */ | |
100 | ||
101 | aemif_clk = clk_get(NULL, "aemif"); | |
102 | if (IS_ERR(aemif_clk)) | |
103 | return PTR_ERR(aemif_clk); | |
104 | ||
105 | clkrate = clk_get_rate(aemif_clk); | |
106 | ||
107 | clkrate /= 1000; /* turn clock into kHz for ease of use */ | |
108 | ||
109 | ta = aemif_calc_rate(t->ta, clkrate, TA_MAX); | |
110 | rhold = aemif_calc_rate(t->rhold, clkrate, RHOLD_MAX); | |
111 | rstrobe = aemif_calc_rate(t->rstrobe, clkrate, RSTROBE_MAX); | |
112 | rsetup = aemif_calc_rate(t->rsetup, clkrate, RSETUP_MAX); | |
113 | whold = aemif_calc_rate(t->whold, clkrate, WHOLD_MAX); | |
114 | wstrobe = aemif_calc_rate(t->wstrobe, clkrate, WSTROBE_MAX); | |
115 | wsetup = aemif_calc_rate(t->wsetup, clkrate, WSETUP_MAX); | |
116 | ||
117 | if (ta < 0 || rhold < 0 || rstrobe < 0 || rsetup < 0 || | |
118 | whold < 0 || wstrobe < 0 || wsetup < 0) { | |
119 | pr_err("%s: cannot get suitable timings\n", __func__); | |
120 | return -EINVAL; | |
121 | } | |
122 | ||
123 | set = TA(ta) | RHOLD(rhold) | RSTROBE(rstrobe) | RSETUP(rsetup) | | |
124 | WHOLD(whold) | WSTROBE(wstrobe) | WSETUP(wsetup); | |
125 | ||
126 | val = __raw_readl(base + offset); | |
127 | val &= ~TIMING_MASK; | |
128 | val |= set; | |
129 | __raw_writel(val, base + offset); | |
130 | ||
131 | return 0; | |
132 | } | |
133 | EXPORT_SYMBOL(davinci_aemif_setup_timing); |