diff options
Diffstat (limited to 'drivers/mfd/cros_ec_spi.c')
| -rw-r--r-- | drivers/mfd/cros_ec_spi.c | 743 |
1 files changed, 0 insertions, 743 deletions
diff --git a/drivers/mfd/cros_ec_spi.c b/drivers/mfd/cros_ec_spi.c deleted file mode 100644 index 2060d1483043..000000000000 --- a/drivers/mfd/cros_ec_spi.c +++ /dev/null @@ -1,743 +0,0 @@ -/* - * ChromeOS EC multi-function device (SPI) - * - * Copyright (C) 2012 Google, Inc - * - * This software is licensed under the terms of the GNU General Public - * License version 2, as published by the Free Software Foundation, and - * may be copied, distributed, and modified under those terms. - * - * This program is distributed in the hope that it will be useful, - * but WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the - * GNU General Public License for more details. - */ - -#include <linux/delay.h> -#include <linux/kernel.h> -#include <linux/module.h> -#include <linux/mfd/cros_ec.h> -#include <linux/mfd/cros_ec_commands.h> -#include <linux/of.h> -#include <linux/platform_device.h> -#include <linux/slab.h> -#include <linux/spi/spi.h> - - -/* The header byte, which follows the preamble */ -#define EC_MSG_HEADER 0xec - -/* - * Number of EC preamble bytes we read at a time. Since it takes - * about 400-500us for the EC to respond there is not a lot of - * point in tuning this. If the EC could respond faster then - * we could increase this so that might expect the preamble and - * message to occur in a single transaction. However, the maximum - * SPI transfer size is 256 bytes, so at 5MHz we need a response - * time of perhaps <320us (200 bytes / 1600 bits). - */ -#define EC_MSG_PREAMBLE_COUNT 32 - -/* - * 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 8 times that to handle clock stretching and other - * paranoia. Note that some battery gas gauge ICs claim to have a - * clock stretch of 144ms in rare situations. That's incentive for - * not directly passing i2c through, but it's too late for that for - * existing hardware. - * - * 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 200 - -/* - * Time between raising the SPI chip select (for the end of a - * transaction) and dropping it again (for the next transaction). - * If we go too fast, the EC will miss the transaction. We know that we - * need at least 70 us with the 16 MHz STM32 EC, so go with 200 us to be - * safe. - */ -#define EC_SPI_RECOVERY_TIME_NS (200 * 1000) - -/** - * struct cros_ec_spi - information about a SPI-connected EC - * - * @spi: SPI device we are connected to - * @last_transfer_ns: time that we last finished a transfer. - * @start_of_msg_delay: used to set the delay_usecs on the spi_transfer that - * is sent when we want to turn on CS at the start of a transaction. - * @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. - */ -struct cros_ec_spi { - struct spi_device *spi; - s64 last_transfer_ns; - unsigned int start_of_msg_delay; - unsigned int end_of_msg_delay; -}; - -static void debug_packet(struct device *dev, const char *name, u8 *ptr, - int len) -{ -#ifdef DEBUG - int i; - - dev_dbg(dev, "%s: ", name); - for (i = 0; i < len; i++) - pr_cont(" %02x", ptr[i]); - - pr_cont("\n"); -#endif -} - -static int terminate_request(struct cros_ec_device *ec_dev) -{ - struct cros_ec_spi *ec_spi = ec_dev->priv; - struct spi_message msg; - struct spi_transfer trans; - int ret; - - /* - * Turn off CS, possibly adding a delay to ensure the rising edge - * doesn't come too soon after the end of the data. - */ - spi_message_init(&msg); - memset(&trans, 0, sizeof(trans)); - trans.delay_usecs = ec_spi->end_of_msg_delay; - spi_message_add_tail(&trans, &msg); - - ret = spi_sync_locked(ec_spi->spi, &msg); - - /* Reset end-of-response timer */ - ec_spi->last_transfer_ns = ktime_get_ns(); - if (ret < 0) { - dev_err(ec_dev->dev, - "cs-deassert spi transfer failed: %d\n", - ret); - } - - return ret; -} - -/** - * receive_n_bytes - receive n bytes from the EC. - * - * Assumes buf is a pointer into the ec_dev->din buffer - */ -static int receive_n_bytes(struct cros_ec_device *ec_dev, u8 *buf, int n) -{ - struct cros_ec_spi *ec_spi = ec_dev->priv; - struct spi_transfer trans; - struct spi_message msg; - int ret; - - BUG_ON(buf - ec_dev->din + n > ec_dev->din_size); - - memset(&trans, 0, sizeof(trans)); - trans.cs_change = 1; - trans.rx_buf = buf; - trans.len = n; - - spi_message_init(&msg); - spi_message_add_tail(&trans, &msg); - ret = spi_sync_locked(ec_spi->spi, &msg); - if (ret < 0) - dev_err(ec_dev->dev, "spi transfer failed: %d\n", ret); - - return ret; -} - -/** - * cros_ec_spi_receive_packet - Receive a packet from the EC. - * - * This function has two phases: reading the preamble bytes (since if we read - * data from the EC before it is ready to send, we just get preamble) and - * reading the actual message. - * - * The received data is placed into ec_dev->din. - * - * @ec_dev: ChromeOS EC device - * @need_len: Number of message bytes we need to read - */ -static int cros_ec_spi_receive_packet(struct cros_ec_device *ec_dev, - int need_len) -{ - struct ec_host_response *response; - u8 *ptr, *end; - int ret; - unsigned long deadline; - int todo; - - BUG_ON(ec_dev->din_size < EC_MSG_PREAMBLE_COUNT); - - /* Receive data until we see the header byte */ - deadline = jiffies + msecs_to_jiffies(EC_MSG_DEADLINE_MS); - while (true) { - unsigned long start_jiffies = jiffies; - - ret = receive_n_bytes(ec_dev, - ec_dev->din, - EC_MSG_PREAMBLE_COUNT); - if (ret < 0) - return ret; - - ptr = ec_dev->din; - for (end = ptr + EC_MSG_PREAMBLE_COUNT; ptr != end; ptr++) { - if (*ptr == EC_SPI_FRAME_START) { - dev_dbg(ec_dev->dev, "msg found at %zd\n", - ptr - ec_dev->din); - break; - } - } - if (ptr != end) - break; - - /* - * 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; - } - } - - /* - * ptr now points to the header byte. Copy any valid data to the - * start of our buffer - */ - todo = end - ++ptr; - BUG_ON(todo < 0 || todo > ec_dev->din_size); - todo = min(todo, need_len); - memmove(ec_dev->din, ptr, todo); - ptr = ec_dev->din + todo; - dev_dbg(ec_dev->dev, "need %d, got %d bytes from preamble\n", - need_len, todo); - need_len -= todo; - - /* If the entire response struct wasn't read, get the rest of it. */ - if (todo < sizeof(*response)) { - ret = receive_n_bytes(ec_dev, ptr, sizeof(*response) - todo); - if (ret < 0) - return -EBADMSG; - ptr += (sizeof(*response) - todo); - todo = sizeof(*response); - } - - response = (struct ec_host_response *)ec_dev->din; - - /* Abort if data_len is too large. */ - if (response->data_len > ec_dev->din_size) - return -EMSGSIZE; - - /* Receive data until we have it all */ - while (need_len > 0) { - /* - * We can't support transfers larger than the SPI FIFO size - * unless we have DMA. We don't have DMA on the ISP SPI ports - * for Exynos. We need a way of asking SPI driver for - * maximum-supported transfer size. - */ - todo = min(need_len, 256); - dev_dbg(ec_dev->dev, "loop, todo=%d, need_len=%d, ptr=%zd\n", - todo, need_len, ptr - ec_dev->din); - - ret = receive_n_bytes(ec_dev, ptr, todo); - if (ret < 0) - return ret; - - ptr += todo; - need_len -= todo; - } - - dev_dbg(ec_dev->dev, "loop done, ptr=%zd\n", ptr - ec_dev->din); - - return 0; -} - -/** - * cros_ec_spi_receive_response - Receive a response from the EC. - * - * This function has two phases: reading the preamble bytes (since if we read - * data from the EC before it is ready to send, we just get preamble) and - * reading the actual message. - * - * The received data is placed into ec_dev->din. - * - * @ec_dev: ChromeOS EC device - * @need_len: Number of message bytes we need to read - */ -static int cros_ec_spi_receive_response(struct cros_ec_device *ec_dev, - int need_len) -{ - u8 *ptr, *end; - int ret; - unsigned long deadline; - int todo; - - BUG_ON(ec_dev->din_size < EC_MSG_PREAMBLE_COUNT); - - /* Receive data until we see the header byte */ - deadline = jiffies + msecs_to_jiffies(EC_MSG_DEADLINE_MS); - while (true) { - unsigned long start_jiffies = jiffies; - - ret = receive_n_bytes(ec_dev, - ec_dev->din, - EC_MSG_PREAMBLE_COUNT); - if (ret < 0) - return ret; - - ptr = ec_dev->din; - for (end = ptr + EC_MSG_PREAMBLE_COUNT; ptr != end; ptr++) { - if (*ptr == EC_SPI_FRAME_START) { - dev_dbg(ec_dev->dev, "msg found at %zd\n", - ptr - ec_dev->din); - break; - } - } - if (ptr != end) - break; - - /* - * 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; - } - } - - /* - * ptr now points to the header byte. Copy any valid data to the - * start of our buffer - */ - todo = end - ++ptr; - BUG_ON(todo < 0 || todo > ec_dev->din_size); - todo = min(todo, need_len); - memmove(ec_dev->din, ptr, todo); - ptr = ec_dev->din + todo; - dev_dbg(ec_dev->dev, "need %d, got %d bytes from preamble\n", - need_len, todo); - need_len -= todo; - - /* Receive data until we have it all */ - while (need_len > 0) { - /* - * We can't support transfers larger than the SPI FIFO size - * unless we have DMA. We don't have DMA on the ISP SPI ports - * for Exynos. We need a way of asking SPI driver for - * maximum-supported transfer size. - */ - todo = min(need_len, 256); - dev_dbg(ec_dev->dev, "loop, todo=%d, need_len=%d, ptr=%zd\n", - todo, need_len, ptr - ec_dev->din); - - ret = receive_n_bytes(ec_dev, ptr, todo); - if (ret < 0) - return ret; - - debug_packet(ec_dev->dev, "interim", ptr, todo); - ptr += todo; - need_len -= todo; - } - - dev_dbg(ec_dev->dev, "loop done, ptr=%zd\n", ptr - ec_dev->din); - - return 0; -} - -/** - * cros_ec_pkt_xfer_spi - Transfer a packet over SPI and receive the reply - * - * @ec_dev: ChromeOS EC device - * @ec_msg: Message to transfer - */ -static int cros_ec_pkt_xfer_spi(struct cros_ec_device *ec_dev, - struct cros_ec_command *ec_msg) -{ - struct ec_host_response *response; - struct cros_ec_spi *ec_spi = ec_dev->priv; - struct spi_transfer trans, trans_delay; - struct spi_message msg; - int i, len; - u8 *ptr; - u8 *rx_buf; - u8 sum; - u8 rx_byte; - int ret = 0, final_ret; - unsigned long delay; - - len = cros_ec_prepare_tx(ec_dev, ec_msg); - dev_dbg(ec_dev->dev, "prepared, len=%d\n", len); - - /* If it's too soon to do another transaction, wait */ - delay = ktime_get_ns() - ec_spi->last_transfer_ns; - if (delay < EC_SPI_RECOVERY_TIME_NS) - ndelay(EC_SPI_RECOVERY_TIME_NS - delay); - - rx_buf = kzalloc(len, GFP_KERNEL); - if (!rx_buf) - return -ENOMEM; - - spi_bus_lock(ec_spi->spi->master); - - /* - * Leave a gap between CS assertion and clocking of data to allow the - * EC time to wakeup. - */ - spi_message_init(&msg); - if (ec_spi->start_of_msg_delay) { - memset(&trans_delay, 0, sizeof(trans_delay)); - trans_delay.delay_usecs = ec_spi->start_of_msg_delay; - spi_message_add_tail(&trans_delay, &msg); - } - - /* Transmit phase - send our message */ - memset(&trans, 0, sizeof(trans)); - trans.tx_buf = ec_dev->dout; - trans.rx_buf = rx_buf; - trans.len = len; - trans.cs_change = 1; - spi_message_add_tail(&trans, &msg); - ret = spi_sync_locked(ec_spi->spi, &msg); - - /* Get the response */ - if (!ret) { - /* Verify that EC can process command */ - for (i = 0; i < len; i++) { - rx_byte = rx_buf[i]; - /* - * Seeing the PAST_END, RX_BAD_DATA, or NOT_READY - * markers are all signs that the EC didn't fully - * receive our command. e.g., if the EC is flashing - * itself, it can't respond to any commands and instead - * clocks out EC_SPI_PAST_END from its SPI hardware - * buffer. Similar occurrences can happen if the AP is - * too slow to clock out data after asserting CS -- the - * EC will abort and fill its buffer with - * EC_SPI_RX_BAD_DATA. - * - * In all cases, these errors should be safe to retry. - * Report -EAGAIN and let the caller decide what to do - * about that. - */ - if (rx_byte == EC_SPI_PAST_END || - rx_byte == EC_SPI_RX_BAD_DATA || - rx_byte == EC_SPI_NOT_READY) { - ret = -EAGAIN; - break; - } - } - } - - if (!ret) - ret = cros_ec_spi_receive_packet(ec_dev, - ec_msg->insize + sizeof(*response)); - else if (ret != -EAGAIN) - dev_err(ec_dev->dev, "spi transfer failed: %d\n", ret); - - final_ret = terminate_request(ec_dev); - - spi_bus_unlock(ec_spi->spi->master); - - if (!ret) - ret = final_ret; - if (ret < 0) - goto exit; - - ptr = ec_dev->din; - - /* check response error code */ - response = (struct ec_host_response *)ptr; - ec_msg->result = response->result; - - ret = cros_ec_check_result(ec_dev, ec_msg); - if (ret) - goto exit; - - len = response->data_len; - sum = 0; - if (len > ec_msg->insize) { - dev_err(ec_dev->dev, "packet too long (%d bytes, expected %d)", - len, ec_msg->insize); - ret = -EMSGSIZE; - goto exit; - } - - for (i = 0; i < sizeof(*response); i++) - sum += ptr[i]; - - /* copy response packet payload and compute checksum */ - memcpy(ec_msg->data, ptr + sizeof(*response), len); - for (i = 0; i < len; i++) - sum += ec_msg->data[i]; - - if (sum) { - dev_err(ec_dev->dev, - "bad packet checksum, calculated %x\n", - sum); - ret = -EBADMSG; - goto exit; - } - - ret = len; -exit: - kfree(rx_buf); - if (ec_msg->command == EC_CMD_REBOOT_EC) - msleep(EC_REBOOT_DELAY_MS); - - return ret; -} - -/** - * cros_ec_cmd_xfer_spi - Transfer a message over SPI and receive the reply - * - * @ec_dev: ChromeOS EC device - * @ec_msg: Message to transfer - */ -static int cros_ec_cmd_xfer_spi(struct cros_ec_device *ec_dev, - struct cros_ec_command *ec_msg) -{ - struct cros_ec_spi *ec_spi = ec_dev->priv; - struct spi_transfer trans; - struct spi_message msg; - int i, len; - u8 *ptr; - u8 *rx_buf; - u8 rx_byte; - int sum; - int ret = 0, final_ret; - unsigned long delay; - - len = cros_ec_prepare_tx(ec_dev, ec_msg); - dev_dbg(ec_dev->dev, "prepared, len=%d\n", len); - - /* If it's too soon to do another transaction, wait */ - delay = ktime_get_ns() - ec_spi->last_transfer_ns; - if (delay < EC_SPI_RECOVERY_TIME_NS) - ndelay(EC_SPI_RECOVERY_TIME_NS - delay); - - rx_buf = kzalloc(len, GFP_KERNEL); - if (!rx_buf) - return -ENOMEM; - - spi_bus_lock(ec_spi->spi->master); - - /* Transmit phase - send our message */ - debug_packet(ec_dev->dev, "out", ec_dev->dout, len); - memset(&trans, 0, sizeof(trans)); - trans.tx_buf = ec_dev->dout; - trans.rx_buf = rx_buf; - trans.len = len; - trans.cs_change = 1; - spi_message_init(&msg); - spi_message_add_tail(&trans, &msg); - ret = spi_sync_locked(ec_spi->spi, &msg); - - /* Get the response */ - if (!ret) { - /* Verify that EC can process command */ - for (i = 0; i < len; i++) { - rx_byte = rx_buf[i]; - /* See comments in cros_ec_pkt_xfer_spi() */ - if (rx_byte == EC_SPI_PAST_END || - rx_byte == EC_SPI_RX_BAD_DATA || - rx_byte == EC_SPI_NOT_READY) { - ret = -EAGAIN; - break; - } - } - } - - if (!ret) - ret = cros_ec_spi_receive_response(ec_dev, - ec_msg->insize + EC_MSG_TX_PROTO_BYTES); - else if (ret != -EAGAIN) - dev_err(ec_dev->dev, "spi transfer failed: %d\n", ret); - - final_ret = terminate_request(ec_dev); - - spi_bus_unlock(ec_spi->spi->master); - - if (!ret) - ret = final_ret; - if (ret < 0) - goto exit; - - ptr = ec_dev->din; - - /* check response error code */ - ec_msg->result = ptr[0]; - ret = cros_ec_check_result(ec_dev, ec_msg); - if (ret) - goto exit; - - len = ptr[1]; - sum = ptr[0] + ptr[1]; - if (len > ec_msg->insize) { - dev_err(ec_dev->dev, "packet too long (%d bytes, expected %d)", - len, ec_msg->insize); - ret = -ENOSPC; - goto exit; - } - - /* copy response packet payload and compute checksum */ - for (i = 0; i < len; i++) { - sum += ptr[i + 2]; - if (ec_msg->insize) - ec_msg->data[i] = ptr[i + 2]; - } - sum &= 0xff; - - debug_packet(ec_dev->dev, "in", ptr, len + 3); - - if (sum != ptr[len + 2]) { - dev_err(ec_dev->dev, - "bad packet checksum, expected %02x, got %02x\n", - sum, ptr[len + 2]); - ret = -EBADMSG; - goto exit; - } - - ret = len; -exit: - kfree(rx_buf); - if (ec_msg->command == EC_CMD_REBOOT_EC) - msleep(EC_REBOOT_DELAY_MS); - - return ret; -} - -static void cros_ec_spi_dt_probe(struct cros_ec_spi *ec_spi, struct device *dev) -{ - struct device_node *np = dev->of_node; - u32 val; - int ret; - - ret = of_property_read_u32(np, "google,cros-ec-spi-pre-delay", &val); - if (!ret) - ec_spi->start_of_msg_delay = val; - - ret = of_property_read_u32(np, "google,cros-ec-spi-msg-delay", &val); - if (!ret) - ec_spi->end_of_msg_delay = val; -} - -static int cros_ec_spi_probe(struct spi_device *spi) -{ - struct device *dev = &spi->dev; - struct cros_ec_device *ec_dev; - struct cros_ec_spi *ec_spi; - int err; - - spi->bits_per_word = 8; - spi->mode = SPI_MODE_0; - err = spi_setup(spi); - if (err < 0) - return err; - - ec_spi = devm_kzalloc(dev, sizeof(*ec_spi), GFP_KERNEL); - if (ec_spi == NULL) - return -ENOMEM; - ec_spi->spi = spi; - ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL); - if (!ec_dev) - return -ENOMEM; - - /* Check for any DT properties */ - cros_ec_spi_dt_probe(ec_spi, dev); - - spi_set_drvdata(spi, ec_dev); - ec_dev->dev = dev; - ec_dev->priv = ec_spi; - ec_dev->irq = spi->irq; - ec_dev->cmd_xfer = cros_ec_cmd_xfer_spi; - ec_dev->pkt_xfer = cros_ec_pkt_xfer_spi; - ec_dev->phys_name = dev_name(&ec_spi->spi->dev); - ec_dev->din_size = EC_MSG_PREAMBLE_COUNT + - sizeof(struct ec_host_response) + - sizeof(struct ec_response_get_protocol_info); - ec_dev->dout_size = sizeof(struct ec_host_request); - - ec_spi->last_transfer_ns = ktime_get_ns(); - - err = cros_ec_register(ec_dev); - if (err) { - dev_err(dev, "cannot register EC\n"); - return err; - } - - device_init_wakeup(&spi->dev, true); - - return 0; -} - -static int cros_ec_spi_remove(struct spi_device *spi) -{ - struct cros_ec_device *ec_dev; - - ec_dev = spi_get_drvdata(spi); - cros_ec_remove(ec_dev); - - return 0; -} - -#ifdef CONFIG_PM_SLEEP -static int cros_ec_spi_suspend(struct device *dev) -{ - struct cros_ec_device *ec_dev = dev_get_drvdata(dev); - - return cros_ec_suspend(ec_dev); -} - -static int cros_ec_spi_resume(struct device *dev) -{ - struct cros_ec_device *ec_dev = dev_get_drvdata(dev); - - return cros_ec_resume(ec_dev); -} -#endif - -static SIMPLE_DEV_PM_OPS(cros_ec_spi_pm_ops, cros_ec_spi_suspend, - cros_ec_spi_resume); - -static const struct of_device_id cros_ec_spi_of_match[] = { - { .compatible = "google,cros-ec-spi", }, - { /* sentinel */ }, -}; -MODULE_DEVICE_TABLE(of, cros_ec_spi_of_match); - -static const struct spi_device_id cros_ec_spi_id[] = { - { "cros-ec-spi", 0 }, - { } -}; -MODULE_DEVICE_TABLE(spi, cros_ec_spi_id); - -static struct spi_driver cros_ec_driver_spi = { - .driver = { - .name = "cros-ec-spi", - .of_match_table = of_match_ptr(cros_ec_spi_of_match), - .pm = &cros_ec_spi_pm_ops, - }, - .probe = cros_ec_spi_probe, - .remove = cros_ec_spi_remove, - .id_table = cros_ec_spi_id, -}; - -module_spi_driver(cros_ec_driver_spi); - -MODULE_LICENSE("GPL v2"); -MODULE_DESCRIPTION("ChromeOS EC multi function device (SPI)"); 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