diff options
Diffstat (limited to 'arch/arm/kernel/iic.c')
| -rw-r--r-- | arch/arm/kernel/iic.c | 239 |
1 files changed, 163 insertions, 76 deletions
diff --git a/arch/arm/kernel/iic.c b/arch/arm/kernel/iic.c index 6eb0122e8..c9a672a32 100644 --- a/arch/arm/kernel/iic.c +++ b/arch/arm/kernel/iic.c @@ -7,20 +7,24 @@ */ #include <linux/delay.h> +#include <linux/errno.h> #include <asm/system.h> -#include <asm/io.h> #include <asm/hardware.h> +#include <asm/io.h> +#include <asm/ioc.h> + +#define FORCE_ONES 0xdc /* * if delay loop has been calibrated then us that, * else use IOC timer 1. */ -static void iic_delay (void) +static void iic_delay(void) { extern unsigned long loops_per_sec; if (loops_per_sec != (1 << 12)) { - udelay(10); + udelay(100); /* was 10 */ return; } else { unsigned long flags; @@ -30,7 +34,7 @@ static void iic_delay (void) outb(255, IOC_T1LTCHH); outb(0, IOC_T1GO); outb(1<<6, IOC_IRQCLRA); /* clear T1 irq */ - outb(4, IOC_T1LTCHL); + outb(10, IOC_T1LTCHL); /* was 4 */ outb(0, IOC_T1LTCHH); outb(0, IOC_T1GO); while ((inb(IOC_IRQSTATA) & (1<<6)) == 0); @@ -38,124 +42,207 @@ static void iic_delay (void) } } -static inline void iic_start (void) +#define IIC_INIT() dat = (inb(IOC_CONTROL) | FORCE_ONES) & ~3 +#define IIC_SET_DAT outb(dat|=1, IOC_CONTROL); +#define IIC_CLR_DAT outb(dat&=~1, IOC_CONTROL); +#define IIC_SET_CLK outb(dat|=2, IOC_CONTROL); +#define IIC_CLR_CLK outb(dat&=~2, IOC_CONTROL); +#define IIC_DELAY iic_delay(); +#define IIC_READ_DATA() (inb(IOC_CONTROL) & 1) + +static inline void iic_set_lines(int clk, int dat) { - unsigned char out; + int old; - out = inb(IOC_CONTROL) | 0xc2; + old = inb(IOC_CONTROL) | FORCE_ONES; - outb(out, IOC_CONTROL); - iic_delay(); + old &= ~3; + + if (clk) + old |= 2; + if (dat) + old |= 1; + + outb(old, IOC_CONTROL); - outb(out ^ 1, IOC_CONTROL); iic_delay(); } -static inline void iic_stop (void) +static inline unsigned int iic_read_data(void) { - unsigned char out; + return inb(IOC_CONTROL) & 1; +} - out = inb(IOC_CONTROL) | 0xc3; +/* + * C: ==~~_ + * D: =~~__ + */ +static inline void iic_start(void) +{ + unsigned int dat; - iic_delay(); - outb(out ^ 1, IOC_CONTROL); + IIC_INIT(); - iic_delay(); - outb(out, IOC_CONTROL); + IIC_SET_DAT + IIC_DELAY + IIC_SET_CLK + IIC_DELAY + + IIC_CLR_DAT + IIC_DELAY + IIC_CLR_CLK + IIC_DELAY } -static int iic_sendbyte (unsigned char b) +/* + * C: __~~ + * D: =__~ + */ +static inline void iic_stop(void) { - unsigned char out, in; - int i; + unsigned int dat; - out = (inb(IOC_CONTROL) & 0xfc) | 0xc0; + IIC_INIT(); - outb(out, IOC_CONTROL); - for (i = 7; i >= 0; i--) { - unsigned char c; - c = out | ((b & (1 << i)) ? 1 : 0); + IIC_CLR_DAT + IIC_DELAY + IIC_SET_CLK + IIC_DELAY + IIC_SET_DAT + IIC_DELAY +} - outb(c, IOC_CONTROL); - iic_delay(); +/* + * C: __~_ + * D: =___ + */ +static inline void iic_acknowledge(void) +{ + unsigned int dat; - outb(c | 2, IOC_CONTROL); - iic_delay(); + IIC_INIT(); - outb(c, IOC_CONTROL); - } - outb(out | 1, IOC_CONTROL); - iic_delay(); + IIC_CLR_DAT + IIC_DELAY + IIC_SET_CLK + IIC_DELAY + IIC_CLR_CLK + IIC_DELAY +} - outb(out | 3, IOC_CONTROL); - iic_delay(); +/* + * C: __~_ + * D: =~H~ + */ +static inline int iic_is_acknowledged(void) +{ + unsigned int dat, ack_bit; - in = inb(IOC_CONTROL) & 1; + IIC_INIT(); - outb(out | 1, IOC_CONTROL); - iic_delay(); + IIC_SET_DAT + IIC_DELAY + IIC_SET_CLK + IIC_DELAY - outb(out, IOC_CONTROL); - iic_delay(); + ack_bit = IIC_READ_DATA(); + + IIC_CLR_CLK + IIC_DELAY + + return ack_bit == 0; +} + +/* + * C: _~__~__~__~__~__~__~__~_ + * D: =DDXDDXDDXDDXDDXDDXDDXDD + */ +static void iic_sendbyte(unsigned int b) +{ + unsigned int dat, i; + + IIC_INIT(); + + for (i = 0; i < 8; i++) { + if (b & 128) + IIC_SET_DAT + else + IIC_CLR_DAT + IIC_DELAY + + IIC_SET_CLK + IIC_DELAY + IIC_CLR_CLK + IIC_DELAY - if(in) { - printk("No acknowledge from RTC\n"); - return 1; - } else - return 0; + b <<= 1; + } } -static unsigned char iic_recvbyte (void) +/* + * C: __~_~_~_~_~_~_~_~_ + * D: =~HHHHHHHHHHHHHHHH + */ +static unsigned char iic_recvbyte(void) { - unsigned char out, in; - int i; + unsigned int dat, i, in; - out = (inb(IOC_CONTROL) & 0xfc) | 0xc0; + IIC_INIT(); + + IIC_SET_DAT + IIC_DELAY - outb(out, IOC_CONTROL); in = 0; - for (i = 7; i >= 0; i--) { - outb(out | 1, IOC_CONTROL); - iic_delay(); - outb(out | 3, IOC_CONTROL); - iic_delay(); - in = (in << 1) | (inb(IOC_CONTROL) & 1); - outb(out | 1, IOC_CONTROL); - iic_delay(); + for (i = 0; i < 8; i++) { + IIC_SET_CLK + IIC_DELAY + + in = (in << 1) | IIC_READ_DATA(); + + IIC_CLR_CLK + IIC_DELAY } - outb(out, IOC_CONTROL); - iic_delay(); - outb(out | 2, IOC_CONTROL); - iic_delay(); return in; } -void iic_control (unsigned char addr, unsigned char loc, unsigned char *buf, int len) +int iic_control (unsigned char addr, unsigned char loc, unsigned char *buf, int len) { - iic_start(); + int i, err = -EIO; - if (iic_sendbyte(addr & 0xfe)) + iic_start(); + iic_sendbyte(addr & 0xfe); + if (!iic_is_acknowledged()) goto error; - if (iic_sendbyte(loc)) + iic_sendbyte(loc); + if (!iic_is_acknowledged()) goto error; if (addr & 1) { - int i; - - for (i = 0; i < len; i++) - if (iic_sendbyte (buf[i])) - break; - } else { - int i; - iic_stop(); iic_start(); iic_sendbyte(addr|1); - for (i = 0; i < len; i++) - buf[i] = iic_recvbyte (); + if (!iic_is_acknowledged()) + goto error; + + for (i = 0; i < len - 1; i++) { + buf[i] = iic_recvbyte(); + iic_acknowledge(); + } + buf[i] = iic_recvbyte(); + } else { + for (i = 0; i < len; i++) { + iic_sendbyte(buf[i]); + + if (!iic_is_acknowledged()) + goto error; + } } + + err = 0; error: iic_stop(); + + return err; } |