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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * Atmel AT93C46 serial eeprom driver | |
3 | * | |
4 | * Brian Murphy <brian.murphy@eicon.com> | |
5 | * | |
6 | */ | |
7 | #include <linux/kernel.h> | |
8 | #include <linux/delay.h> | |
9 | #include <asm/lasat/lasat.h> | |
10 | #include <linux/module.h> | |
11 | #include <linux/init.h> | |
12 | ||
13 | #include "at93c.h" | |
14 | ||
15 | #define AT93C_ADDR_SHIFT 7 | |
16 | #define AT93C_ADDR_MAX ((1 << AT93C_ADDR_SHIFT) - 1) | |
17 | #define AT93C_RCMD (0x6 << AT93C_ADDR_SHIFT) | |
18 | #define AT93C_WCMD (0x5 << AT93C_ADDR_SHIFT) | |
19 | #define AT93C_WENCMD 0x260 | |
20 | #define AT93C_WDSCMD 0x200 | |
21 | ||
22 | struct at93c_defs *at93c; | |
23 | ||
24 | static void at93c_reg_write(u32 val) | |
25 | { | |
26 | *at93c->reg = val; | |
27 | } | |
28 | ||
29 | static u32 at93c_reg_read(void) | |
30 | { | |
31 | u32 tmp = *at93c->reg; | |
32 | return tmp; | |
33 | } | |
34 | ||
35 | static u32 at93c_datareg_read(void) | |
36 | { | |
37 | u32 tmp = *at93c->rdata_reg; | |
38 | return tmp; | |
39 | } | |
40 | ||
41 | static void at93c_cycle_clk(u32 data) | |
42 | { | |
43 | at93c_reg_write(data | at93c->clk); | |
44 | lasat_ndelay(250); | |
45 | at93c_reg_write(data & ~at93c->clk); | |
46 | lasat_ndelay(250); | |
47 | } | |
48 | ||
49 | static void at93c_write_databit(u8 bit) | |
50 | { | |
51 | u32 data = at93c_reg_read(); | |
52 | if (bit) | |
53 | data |= 1 << at93c->wdata_shift; | |
54 | else | |
55 | data &= ~(1 << at93c->wdata_shift); | |
56 | ||
57 | at93c_reg_write(data); | |
58 | lasat_ndelay(100); | |
59 | at93c_cycle_clk(data); | |
60 | } | |
61 | ||
62 | static unsigned int at93c_read_databit(void) | |
63 | { | |
64 | u32 data; | |
65 | ||
66 | at93c_cycle_clk(at93c_reg_read()); | |
67 | data = (at93c_datareg_read() >> at93c->rdata_shift) & 1; | |
68 | return data; | |
69 | } | |
70 | ||
71 | static u8 at93c_read_byte(void) | |
72 | { | |
73 | int i; | |
74 | u8 data = 0; | |
75 | ||
76 | for (i = 0; i<=7; i++) { | |
77 | data <<= 1; | |
78 | data |= at93c_read_databit(); | |
79 | } | |
80 | return data; | |
81 | } | |
82 | ||
83 | static void at93c_write_bits(u32 data, int size) | |
84 | { | |
85 | int i; | |
86 | int shift = size - 1; | |
87 | u32 mask = (1 << shift); | |
88 | ||
89 | for (i = 0; i < size; i++) { | |
90 | at93c_write_databit((data & mask) >> shift); | |
91 | data <<= 1; | |
92 | } | |
93 | } | |
94 | ||
95 | static void at93c_init_op(void) | |
96 | { | |
97 | at93c_reg_write((at93c_reg_read() | at93c->cs) & ~at93c->clk & ~(1 << at93c->rdata_shift)); | |
98 | lasat_ndelay(50); | |
99 | } | |
100 | ||
101 | static void at93c_end_op(void) | |
102 | { | |
103 | at93c_reg_write(at93c_reg_read() & ~at93c->cs); | |
104 | lasat_ndelay(250); | |
105 | } | |
106 | ||
107 | static void at93c_wait(void) | |
108 | { | |
109 | at93c_init_op(); | |
110 | while (!at93c_read_databit()) | |
111 | ; | |
112 | at93c_end_op(); | |
113 | }; | |
114 | ||
115 | static void at93c_disable_wp(void) | |
116 | { | |
117 | at93c_init_op(); | |
118 | at93c_write_bits(AT93C_WENCMD, 10); | |
119 | at93c_end_op(); | |
120 | } | |
121 | ||
122 | static void at93c_enable_wp(void) | |
123 | { | |
124 | at93c_init_op(); | |
125 | at93c_write_bits(AT93C_WDSCMD, 10); | |
126 | at93c_end_op(); | |
127 | } | |
128 | ||
129 | u8 at93c_read(u8 addr) | |
130 | { | |
131 | u8 byte; | |
132 | at93c_init_op(); | |
133 | at93c_write_bits((addr & AT93C_ADDR_MAX)|AT93C_RCMD, 10); | |
134 | byte = at93c_read_byte(); | |
135 | at93c_end_op(); | |
136 | return byte; | |
137 | } | |
138 | ||
139 | void at93c_write(u8 addr, u8 data) | |
140 | { | |
141 | at93c_disable_wp(); | |
142 | at93c_init_op(); | |
143 | at93c_write_bits((addr & AT93C_ADDR_MAX)|AT93C_WCMD, 10); | |
144 | at93c_write_bits(data, 8); | |
145 | at93c_end_op(); | |
146 | at93c_wait(); | |
147 | at93c_enable_wp(); | |
148 | } |