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 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} 150