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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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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;
}