From 0a355aeb24081e4538d4d424cd189f16c0bbd983 Mon Sep 17 00:00:00 2001 From: Evan Nimmo Date: Wed, 9 Sep 2020 08:32:47 +1200 Subject: i2c: algo: pca: Reapply i2c bus settings after reset If something goes wrong (such as the SCL being stuck low) then we need to reset the PCA chip. The issue with this is that on reset we lose all config settings and the chip ends up in a disabled state which results in a lock up/high CPU usage. We need to re-apply any configuration that had previously been set and re-enable the chip. Signed-off-by: Evan Nimmo Reviewed-by: Chris Packham Reviewed-by: Andy Shevchenko Signed-off-by: Wolfram Sang --- drivers/i2c/algos/i2c-algo-pca.c | 35 +++++++++++++++++++++++------------ 1 file changed, 23 insertions(+), 12 deletions(-) (limited to 'drivers') diff --git a/drivers/i2c/algos/i2c-algo-pca.c b/drivers/i2c/algos/i2c-algo-pca.c index 710fbef9a9c2..384af88e58ad 100644 --- a/drivers/i2c/algos/i2c-algo-pca.c +++ b/drivers/i2c/algos/i2c-algo-pca.c @@ -41,8 +41,22 @@ static void pca_reset(struct i2c_algo_pca_data *adap) pca_outw(adap, I2C_PCA_INDPTR, I2C_PCA_IPRESET); pca_outw(adap, I2C_PCA_IND, 0xA5); pca_outw(adap, I2C_PCA_IND, 0x5A); + + /* + * After a reset we need to re-apply any configuration + * (calculated in pca_init) to get the bus in a working state. + */ + pca_outw(adap, I2C_PCA_INDPTR, I2C_PCA_IMODE); + pca_outw(adap, I2C_PCA_IND, adap->bus_settings.mode); + pca_outw(adap, I2C_PCA_INDPTR, I2C_PCA_ISCLL); + pca_outw(adap, I2C_PCA_IND, adap->bus_settings.tlow); + pca_outw(adap, I2C_PCA_INDPTR, I2C_PCA_ISCLH); + pca_outw(adap, I2C_PCA_IND, adap->bus_settings.thi); + + pca_set_con(adap, I2C_PCA_CON_ENSIO); } else { adap->reset_chip(adap->data); + pca_set_con(adap, I2C_PCA_CON_ENSIO | adap->bus_settings.clock_freq); } } @@ -423,13 +437,14 @@ static int pca_init(struct i2c_adapter *adap) " Use the nominal frequency.\n", adap->name); } - pca_reset(pca_data); - clock = pca_clock(pca_data); printk(KERN_INFO "%s: Clock frequency is %dkHz\n", adap->name, freqs[clock]); - pca_set_con(pca_data, I2C_PCA_CON_ENSIO | clock); + /* Store settings as these will be needed when the PCA chip is reset */ + pca_data->bus_settings.clock_freq = clock; + + pca_reset(pca_data); } else { int clock; int mode; @@ -496,19 +511,15 @@ static int pca_init(struct i2c_adapter *adap) thi = tlow * min_thi / min_tlow; } + /* Store settings as these will be needed when the PCA chip is reset */ + pca_data->bus_settings.mode = mode; + pca_data->bus_settings.tlow = tlow; + pca_data->bus_settings.thi = thi; + pca_reset(pca_data); printk(KERN_INFO "%s: Clock frequency is %dHz\n", adap->name, clock * 100); - - pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IMODE); - pca_outw(pca_data, I2C_PCA_IND, mode); - pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ISCLL); - pca_outw(pca_data, I2C_PCA_IND, tlow); - pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ISCLH); - pca_outw(pca_data, I2C_PCA_IND, thi); - - pca_set_con(pca_data, I2C_PCA_CON_ENSIO); } udelay(500); /* 500 us for oscillator to stabilise */ -- cgit v1.2.3