diff options
Diffstat (limited to 'drivers/mfd/cros_ec_spi.c')
| -rw-r--r-- | drivers/mfd/cros_ec_spi.c | 67 |
1 files changed, 50 insertions, 17 deletions
diff --git a/drivers/mfd/cros_ec_spi.c b/drivers/mfd/cros_ec_spi.c index 84af8d7a429..0b8d3282916 100644 --- a/drivers/mfd/cros_ec_spi.c +++ b/drivers/mfd/cros_ec_spi.c @@ -39,14 +39,22 @@ #define EC_MSG_PREAMBLE_COUNT 32 /* - * We must get a response from the EC in 5ms. This is a very long - * time, but the flash write command can take 2-3ms. The EC command - * processing is currently not very fast (about 500us). We could - * look at speeding this up and making the flash write command a - * 'slow' command, requiring a GET_STATUS wait loop, like flash - * erase. - */ -#define EC_MSG_DEADLINE_MS 5 + * Allow for a long time for the EC to respond. We support i2c + * tunneling and support fairly long messages for the tunnel (249 + * bytes long at the moment). If we're talking to a 100 kHz device + * on the other end and need to transfer ~256 bytes, then we need: + * 10 us/bit * ~10 bits/byte * ~256 bytes = ~25ms + * + * We'll wait 4 times that to handle clock stretching and other + * paranoia. + * + * It's pretty unlikely that we'll really see a 249 byte tunnel in + * anything other than testing. If this was more common we might + * consider having slow commands like this require a GET_STATUS + * wait loop. The 'flash write' command would be another candidate + * for this, clocking in at 2-3ms. + */ +#define EC_MSG_DEADLINE_MS 100 /* * Time between raising the SPI chip select (for the end of a @@ -65,11 +73,13 @@ * if no record * @end_of_msg_delay: used to set the delay_usecs on the spi_transfer that * is sent when we want to turn off CS at the end of a transaction. + * @lock: mutex to ensure only one user of cros_ec_command_spi_xfer at a time */ struct cros_ec_spi { struct spi_device *spi; s64 last_transfer_ns; unsigned int end_of_msg_delay; + struct mutex lock; }; static void debug_packet(struct device *dev, const char *name, u8 *ptr, @@ -111,7 +121,9 @@ static int cros_ec_spi_receive_response(struct cros_ec_device *ec_dev, /* Receive data until we see the header byte */ deadline = jiffies + msecs_to_jiffies(EC_MSG_DEADLINE_MS); - do { + while (true) { + unsigned long start_jiffies = jiffies; + memset(&trans, 0, sizeof(trans)); trans.cs_change = 1; trans.rx_buf = ptr = ec_dev->din; @@ -132,12 +144,19 @@ static int cros_ec_spi_receive_response(struct cros_ec_device *ec_dev, break; } } + if (ptr != end) + break; - if (time_after(jiffies, deadline)) { + /* + * Use the time at the start of the loop as a timeout. This + * gives us one last shot at getting the transfer and is useful + * in case we got context switched out for a while. + */ + if (time_after(start_jiffies, deadline)) { dev_warn(ec_dev->dev, "EC failed to respond in time\n"); return -ETIMEDOUT; } - } while (ptr == end); + } /* * ptr now points to the header byte. Copy any valid data to the @@ -208,6 +227,13 @@ static int cros_ec_command_spi_xfer(struct cros_ec_device *ec_dev, int ret = 0, final_ret; struct timespec ts; + /* + * We have the shared ec_dev buffer plus we do lots of separate spi_sync + * calls, so we need to make sure only one person is using this at a + * time. + */ + mutex_lock(&ec_spi->lock); + len = cros_ec_prepare_tx(ec_dev, ec_msg); dev_dbg(ec_dev->dev, "prepared, len=%d\n", len); @@ -219,7 +245,7 @@ static int cros_ec_command_spi_xfer(struct cros_ec_device *ec_dev, ktime_get_ts(&ts); delay = timespec_to_ns(&ts) - ec_spi->last_transfer_ns; if (delay < EC_SPI_RECOVERY_TIME_NS) - ndelay(delay); + ndelay(EC_SPI_RECOVERY_TIME_NS - delay); } /* Transmit phase - send our message */ @@ -260,7 +286,7 @@ static int cros_ec_command_spi_xfer(struct cros_ec_device *ec_dev, ret = final_ret; if (ret < 0) { dev_err(ec_dev->dev, "spi transfer failed: %d\n", ret); - return ret; + goto exit; } /* check response error code */ @@ -269,14 +295,16 @@ static int cros_ec_command_spi_xfer(struct cros_ec_device *ec_dev, dev_warn(ec_dev->dev, "command 0x%02x returned an error %d\n", ec_msg->cmd, ptr[0]); debug_packet(ec_dev->dev, "in_err", ptr, len); - return -EINVAL; + ret = -EINVAL; + goto exit; } len = ptr[1]; sum = ptr[0] + ptr[1]; if (len > ec_msg->in_len) { dev_err(ec_dev->dev, "packet too long (%d bytes, expected %d)", len, ec_msg->in_len); - return -ENOSPC; + ret = -ENOSPC; + goto exit; } /* copy response packet payload and compute checksum */ @@ -293,10 +321,14 @@ static int cros_ec_command_spi_xfer(struct cros_ec_device *ec_dev, dev_err(ec_dev->dev, "bad packet checksum, expected %02x, got %02x\n", sum, ptr[len + 2]); - return -EBADMSG; + ret = -EBADMSG; + goto exit; } - return 0; + ret = 0; +exit: + mutex_unlock(&ec_spi->lock); + return ret; } static void cros_ec_spi_dt_probe(struct cros_ec_spi *ec_spi, struct device *dev) @@ -327,6 +359,7 @@ static int cros_ec_spi_probe(struct spi_device *spi) if (ec_spi == NULL) return -ENOMEM; ec_spi->spi = spi; + mutex_init(&ec_spi->lock); ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL); if (!ec_dev) return -ENOMEM; |