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Reset i2c slave devices during init on mpc5xxx cpus

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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>
This commit is contained in:
Eric Millbrandt 2009-09-03 08:09:44 -05:00 committed by Heiko Schocher
parent 9f23ca42b3
commit 5da71efa18
3 changed files with 57 additions and 0 deletions
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7
README
View file

@ -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)

49
cpu/mpc5xxx/i2c.c
View file

@ -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(void)
{
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(&regs->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(&regs->mcr, I2C_EN|I2C_STA|I2C_TX, I2C_INIT_MASK);
udelay(delay);
mpc_reg_out(&regs->mcr, 0, I2C_INIT_MASK);
udelay(delay);
}
mpc_reg_out(&regs->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(&regs->mcr, I2C_EN, I2C_INIT_MASK);
mpc_reg_out(&regs->msr, 0, I2C_IF);
#if defined(CONFIG_SYS_I2C_INIT_MPC5XXX)
send_reset();
#endif
return;
}

1
include/configs/galaxy5200.h
View file

@ -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