blob: 793e234719a66c1539861e36483a380bbd08310f [file] [log] [blame]
Brian Murphy1f21d2b2007-08-21 22:34:16 +02001/*
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
22struct at93c_defs *at93c;
23
24static void at93c_reg_write(u32 val)
25{
26 *at93c->reg = val;
27}
28
29static u32 at93c_reg_read(void)
30{
31 u32 tmp = *at93c->reg;
32 return tmp;
33}
34
35static u32 at93c_datareg_read(void)
36{
37 u32 tmp = *at93c->rdata_reg;
38 return tmp;
39}
40
41static 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
49static 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
62static 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
71static 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
83static 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
95static void at93c_init_op(void)
96{
97 at93c_reg_write((at93c_reg_read() | at93c->cs) &
98 ~at93c->clk & ~(1 << at93c->rdata_shift));
99 lasat_ndelay(50);
100}
101
102static void at93c_end_op(void)
103{
104 at93c_reg_write(at93c_reg_read() & ~at93c->cs);
105 lasat_ndelay(250);
106}
107
108static void at93c_wait(void)
109{
110 at93c_init_op();
111 while (!at93c_read_databit())
112 ;
113 at93c_end_op();
114};
115
116static void at93c_disable_wp(void)
117{
118 at93c_init_op();
119 at93c_write_bits(AT93C_WENCMD, 10);
120 at93c_end_op();
121}
122
123static void at93c_enable_wp(void)
124{
125 at93c_init_op();
126 at93c_write_bits(AT93C_WDSCMD, 10);
127 at93c_end_op();
128}
129
130u8 at93c_read(u8 addr)
131{
132 u8 byte;
133 at93c_init_op();
134 at93c_write_bits((addr & AT93C_ADDR_MAX)|AT93C_RCMD, 10);
135 byte = at93c_read_byte();
136 at93c_end_op();
137 return byte;
138}
139
140void at93c_write(u8 addr, u8 data)
141{
142 at93c_disable_wp();
143 at93c_init_op();
144 at93c_write_bits((addr & AT93C_ADDR_MAX)|AT93C_WCMD, 10);
145 at93c_write_bits(data, 8);
146 at93c_end_op();
147 at93c_wait();
148 at93c_enable_wp();
149}