diff options
Diffstat (limited to 'src/device/software_i2c.c')
| -rw-r--r-- | src/device/software_i2c.c | 54 |
1 files changed, 29 insertions, 25 deletions
diff --git a/src/device/software_i2c.c b/src/device/software_i2c.c index ec6722bbed..402f1d4131 100644 --- a/src/device/software_i2c.c +++ b/src/device/software_i2c.c @@ -29,6 +29,11 @@ #define spew(...) do { if (SPEW) printk(BIOS_SPEW, ##__VA_ARGS__); } while (0) +#define ERR_NACK -2 +#define ERR_TIMEOUT -3 +#define ERR_ARB -4 +#define ERR_WEDGE -5 + struct software_i2c_ops *software_i2c[SOFTWARE_I2C_MAX_BUS]; /* @@ -71,7 +76,7 @@ static int wait_for_scl(unsigned bus, const char *error_context) if (!__wait(bus, TIMEOUT_US, 1)) { printk(BIOS_ERR, "software_i2c(%d): ERROR: Clock stretching " "timeout %s!\n", bus, error_context); - return -1; + return ERR_TIMEOUT; } return 0; @@ -88,13 +93,13 @@ static int start_cond(unsigned bus) /* Might need to wait for clock stretching if repeated start. */ software_i2c[bus]->set_scl(bus, 1); if (wait_for_scl(bus, "before start condition")) - return -1; + return ERR_TIMEOUT; wait(bus); /* Repeated start setup time, minimum 4.7us */ if (!software_i2c[bus]->get_sda(bus)) { printk(BIOS_ERR, "software_i2c(%d): Arbitration lost trying " "to send start condition!\n", bus); - return -1; + return ERR_ARB; } /* SCL is high, transition SDA low as first part of start condition. */ @@ -121,7 +126,7 @@ static int stop_cond(unsigned bus) assert(!software_i2c[bus]->get_scl(bus)); software_i2c[bus]->set_scl(bus, 1); if (wait_for_scl(bus, "before stop condition")) - return -1; + return ERR_TIMEOUT; wait(bus); /* Stop bit setup time, minimum 4us */ /* SCL is high, transition SDA high to signal stop condition. */ @@ -148,20 +153,20 @@ static int out_bit(unsigned bus, int bit) if (bit && !software_i2c[bus]->get_sda(bus)) { printk(BIOS_ERR, "software_i2c(%d): ERROR: SDA wedged low " "by slave before clock pulse on transmit!\n", bus); - return -1; + return ERR_WEDGE; } /* Clock stretching */ assert(!software_i2c[bus]->get_scl(bus)); software_i2c[bus]->set_scl(bus, 1); if (wait_for_scl(bus, "on transmit")) - return -1; + return ERR_TIMEOUT; wait(bus); if (bit && !software_i2c[bus]->get_sda(bus)) { printk(BIOS_ERR, "software_i2c(%d): ERROR: SDA wedged low " "by slave after clock pulse on transmit!\n", bus); - return -1; + return ERR_WEDGE; } assert(software_i2c[bus]->get_scl(bus)); @@ -185,7 +190,7 @@ static int in_bit(unsigned bus) assert(!software_i2c[bus]->get_scl(bus)); software_i2c[bus]->set_scl(bus, 1); if (wait_for_scl(bus, "on receive")) - return -1; + return ERR_TIMEOUT; /* SCL is high, now data is valid */ bit = software_i2c[bus]->get_sda(bus); @@ -202,11 +207,11 @@ static int in_bit(unsigned bus) static int out_byte(unsigned bus, u8 byte) { unsigned bit; - int nack; + int nack, ret; for (bit = 0; bit < 8; bit++) - if (out_bit(bus, (byte >> (7 - bit)) & 0x1) < 0) - return -1; + if ((ret = out_bit(bus, (byte >> (7 - bit)) & 0x1)) < 0) + return ret; nack = in_bit(bus); @@ -214,22 +219,22 @@ static int out_byte(unsigned bus, u8 byte) printk(BIOS_DEBUG, "software_i2c(%d): wrote byte 0x%02x, " "received %s\n", bus, byte, nack ? "NAK" : "ACK"); - return nack; + return nack > 0 ? ERR_NACK : nack; } static int in_byte(unsigned bus, int ack) { u8 byte = 0; - int i; + int i, ret; for (i = 0; i < 8; ++i) { int bit = in_bit(bus); if (bit < 0) - return -1; + return bit; byte = (byte << 1) | bit; } - if (out_bit(bus, !ack) < 0) - return -1; + if ((ret = out_bit(bus, !ack)) < 0) + return ret; if (DEBUG) printk(BIOS_DEBUG, "software_i2c(%d): read byte 0x%02x, " @@ -240,17 +245,16 @@ static int in_byte(unsigned bus, int ack) int software_i2c_transfer(unsigned bus, struct i2c_msg *segments, int count) { - int i; + int i, ret; struct i2c_msg *seg; for (seg = segments; seg - segments < count; seg++) { - if (start_cond(bus) < 0) - return -1; + if ((ret = start_cond(bus)) < 0) + return ret; const u8 addr_dir = seg->slave << 1 | !!(seg->flags & I2C_M_RD); - if (out_byte(bus, addr_dir) < 0) - return -1; + if ((ret = out_byte(bus, addr_dir)) < 0) + return ret; for (i = 0; i < seg->len; i++) { - int ret; if (seg->flags & I2C_M_RD) { ret = in_byte(bus, i < seg->len - 1); seg->buf[i] = (u8)ret; @@ -258,11 +262,11 @@ int software_i2c_transfer(unsigned bus, struct i2c_msg *segments, int count) ret = out_byte(bus, seg->buf[i]); } if (ret < 0) - return -1; + return ret; } } - if (stop_cond(bus) < 0) - return -1; + if ((ret = stop_cond(bus)) < 0) + return ret; return 0; } |