Reset any i2c devices that may have been interrupted during a system reset. Normally this would be accomplished by clocking the line until SCL and SDA are released and then sending a start condtiion (From an Atmel datasheet). There is no direct access to the i2c pins so instead create start commands through the i2c interface. Send a start command then delay for the SDA Hold time, repeat this by disabling/enabling the bus a total of 9 times.
Signed-off-by: Eric Millbrandt emillbrandt@dekaresearch.com ---
Heiko,
I was able to implement a i2c reset function with features common to all mpc5xxx cpu. Nothing was left from the first implementation, so I am submitting this as a new patch.
Thanks Eric
README | 7 ++++++ cpu/mpc5xxx/i2c.c | 49 ++++++++++++++++++++++++++++++++++++++++++ include/configs/galaxy5200.h | 1 + 3 files changed, 57 insertions(+), 0 deletions(-)
diff --git a/README b/README index 246ae2b..6ccb2fe 100644 --- a/README +++ b/README @@ -1366,6 +1366,13 @@ The following options need to be configured: therefore be cleared to 0 (See, eg, MPC823e User's Manual p.16-473). So, set CONFIG_SYS_I2C_SLAVE to 0.
+ CONFIG_SYS_I2C_INIT_MPC5XXX + + When a board is reset during an i2c bus transfer + chips might think that the current transfer is still + in progress. Reset the slave devices by sending start + commands until the slave device responds. + That's all that's required for CONFIG_HARD_I2C.
If you use the software i2c interface (CONFIG_SOFT_I2C) diff --git a/cpu/mpc5xxx/i2c.c b/cpu/mpc5xxx/i2c.c index 2341932..70a46be 100644 --- a/cpu/mpc5xxx/i2c.c +++ b/cpu/mpc5xxx/i2c.c @@ -207,6 +207,52 @@ static int receive_bytes(uchar chip, char *buf, int len) return 0; }
+#if defined(CONFIG_SYS_I2C_INIT_MPC5XXX) + +#define FDR510(x) (u8) (((x & 0x20) >> 3) | (x & 0x3)) +#define FDR432(x) (u8) ((x & 0x1C) >> 2) +/* + * Reset any i2c devices that may have been interrupted during a system reset. + * Normally this would be accomplished by clocking the line until SCL and SDA + * are released and then sending a start condtiion (From an Atmel datasheet). + * There is no direct access to the i2c pins so instead create start commands + * through the i2c interface. Send a start command then delay for the SDA Hold + * time, repeat this by disabling/enabling the bus a total of 9 times. + */ +static void send_reset() +{ + struct mpc5xxx_i2c *regs = (struct mpc5xxx_i2c *)I2C_BASE; + int i; + u32 delay; + u8 fdr; + int SDA_Tap[] = { 3, 3, 4, 4, 1, 1, 2, 2}; + struct mpc5xxx_i2c_tap scltap[] = { + {4, 1}, + {4, 2}, + {6, 4}, + {6, 8}, + {14, 16}, + {30, 32}, + {62, 64}, + {126, 128} + }; + + fdr = (u8)mpc_reg_in(®s->mfdr); + + delay = scltap[FDR432(fdr)].scl2tap + ((SDA_Tap[FDR510(fdr)] - 1) * \ + scltap[FDR432(fdr)].tap2tap) + 3; + + for (i = 0; i < 9; i++) { + mpc_reg_out(®s->mcr, I2C_EN|I2C_STA|I2C_TX, I2C_INIT_MASK); + udelay(delay); + mpc_reg_out(®s->mcr, 0, I2C_INIT_MASK); + udelay(delay); + } + + mpc_reg_out(®s->mcr, I2C_EN, I2C_INIT_MASK); +} +#endif /* CONFIG_SYS_I2c_INIT_MPC5XXX */ + /**************** I2C API ****************/
void i2c_init(int speed, int saddr) @@ -225,6 +271,9 @@ void i2c_init(int speed, int saddr) mpc_reg_out(®s->mcr, I2C_EN, I2C_INIT_MASK); mpc_reg_out(®s->msr, 0, I2C_IF);
+#if defined(CONFIG_SYS_I2C_INIT_MPC5XXX) + send_reset(); +#endif return; }
diff --git a/include/configs/galaxy5200.h b/include/configs/galaxy5200.h index 8d530d8..2ba5f0f 100644 --- a/include/configs/galaxy5200.h +++ b/include/configs/galaxy5200.h @@ -110,6 +110,7 @@ #define CONFIG_SYS_I2C_MODULE 2 /* Select I2C module #1 or #2 */ #define CONFIG_SYS_I2C_SPEED 100000 /* 100 kHz */ #define CONFIG_SYS_I2C_SLAVE 0x7F +#define CONFIG_SYS_I2C_INIT_MPC5XXX /* Reset devices on i2c bus */
/* * EEPROM CAT24WC32 configuration