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.
Unified · Split
| @@ -41,8 +41,22 @@ static void pca_reset(struct i2c_algo_pca_data *adap) · 40 unmodified lines | ||
| 41 | 41 | pca_outw(adap, I2C_PCA_INDPTR, I2C_PCA_IPRESET); |
| 42 | 42 | pca_outw(adap, I2C_PCA_IND, 0xA5); |
| 43 | 43 | pca_outw(adap, I2C_PCA_IND, 0x5A); |
| 44 | + | |
| 45 | + /* | |
| 46 | + * After a reset we need to re-apply any configuration | |
| 47 | + * (calculated in pca_init) to get the bus in a working state. | |
| 48 | + */ | |
| 49 | + pca_outw(adap, I2C_PCA_INDPTR, I2C_PCA_IMODE); | |
| 50 | + pca_outw(adap, I2C_PCA_IND, adap->bus_settings.mode); | |
| 51 | + pca_outw(adap, I2C_PCA_INDPTR, I2C_PCA_ISCLL); | |
| 52 | + pca_outw(adap, I2C_PCA_IND, adap->bus_settings.tlow); | |
| 53 | + pca_outw(adap, I2C_PCA_INDPTR, I2C_PCA_ISCLH); | |
| 54 | + pca_outw(adap, I2C_PCA_IND, adap->bus_settings.thi); | |
| 55 | + | |
| 56 | + pca_set_con(adap, I2C_PCA_CON_ENSIO); | |
| 44 | 57 | } else { |
| 45 | 58 | adap->reset_chip(adap->data); |
| 59 | + pca_set_con(adap, I2C_PCA_CON_ENSIO | adap->bus_settings.clock_freq); | |
| 46 | 60 | } |
| 47 | 61 | } |
| 48 | 62 | |
| @@ -423,13 +437,14 @@ static int pca_init(struct i2c_adapter *adap) · 374 unmodified lines | ||
| 423 | 437 | " Use the nominal frequency.\n", adap->name); |
| 424 | 438 | } |
| 425 | 439 | |
| 426 | − pca_reset(pca_data); | |
| 427 | − | |
| 428 | 440 | clock = pca_clock(pca_data); |
| 429 | 441 | printk(KERN_INFO "%s: Clock frequency is %dkHz\n", |
| 430 | 442 | adap->name, freqs[clock]); |
| 431 | 443 | |
| 432 | − pca_set_con(pca_data, I2C_PCA_CON_ENSIO | clock); | |
| 444 | + /* Store settings as these will be needed when the PCA chip is reset */ | |
| 445 | + pca_data->bus_settings.clock_freq = clock; | |
| 446 | + | |
| 447 | + pca_reset(pca_data); | |
| 433 | 448 | } else { |
| 434 | 449 | int clock; |
| 435 | 450 | int mode; |
| @@ -496,19 +511,15 @@ static int pca_init(struct i2c_adapter *adap) · 60 unmodified lines | ||
| 496 | 511 | thi = tlow * min_thi / min_tlow; |
| 497 | 512 | } |
| 498 | 513 | |
| 514 | + /* Store settings as these will be needed when the PCA chip is reset */ | |
| 515 | + pca_data->bus_settings.mode = mode; | |
| 516 | + pca_data->bus_settings.tlow = tlow; | |
| 517 | + pca_data->bus_settings.thi = thi; | |
| 518 | + | |
| 499 | 519 | pca_reset(pca_data); |
| 500 | 520 | |
| 501 | 521 | printk(KERN_INFO |
| 502 | 522 | "%s: Clock frequency is %dHz\n", adap->name, clock * 100); |
| 503 | − | |
| 504 | − pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IMODE); | |
| 505 | − pca_outw(pca_data, I2C_PCA_IND, mode); | |
| 506 | − pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ISCLL); | |
| 507 | − pca_outw(pca_data, I2C_PCA_IND, tlow); | |
| 508 | − pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ISCLH); | |
| 509 | − pca_outw(pca_data, I2C_PCA_IND, thi); | |
| 510 | − | |
| 511 | − pca_set_con(pca_data, I2C_PCA_CON_ENSIO); | |
| 512 | 523 | } |
| 513 | 524 | udelay(500); /* 500 us for oscillator to stabilise */ |
| 514 | 525 | |
| @@ -53,6 +53,20 @@ · 52 unmodified lines | ||
| 53 | 53 | #define I2C_PCA_CON_SI 0x08 /* Serial Interrupt */ |
| 54 | 54 | #define I2C_PCA_CON_CR 0x07 /* Clock Rate (MASK) */ |
| 55 | 55 | |
| 56 | +/** | |
| 57 | + * struct pca_i2c_bus_settings - The configured PCA i2c bus settings | |
| 58 | + * @mode: Configured i2c bus mode | |
| 59 | + * @tlow: Configured SCL LOW period | |
| 60 | + * @thi: Configured SCL HIGH period | |
| 61 | + * @clock_freq: The configured clock frequency | |
| 62 | + */ | |
| 63 | +struct pca_i2c_bus_settings { | |
| 64 | + int mode; | |
| 65 | + int tlow; | |
| 66 | + int thi; | |
| 67 | + int clock_freq; | |
| 68 | +}; | |
| 69 | + | |
| 56 | 70 | struct i2c_algo_pca_data { |
| 57 | 71 | void *data; /* private low level data */ |
| 58 | 72 | void (*write_byte) (void *data, int reg, int val); |
| @@ -64,6 +78,7 @@ struct i2c_algo_pca_data { · 5 unmodified lines | ||
| 64 | 78 | * For PCA9665, use the frequency you want here. */ |
| 65 | 79 | unsigned int i2c_clock; |
| 66 | 80 | unsigned int chip; |
| 81 | + struct pca_i2c_bus_settings bus_settings; | |
| 67 | 82 | }; |
| 68 | 83 | |
| 69 | 84 | int i2c_pca_add_bus(struct i2c_adapter *); |