[PATCH v7 4/8] mfd: cros_ec: add proto v3 skeleton

Javier Martinez Canillas
2015-06-09T11:05:46Z

From: Stephen Barber <smbarber@chromium.org>

Add support in cros_ec.c to handle EC host command protocol v3.
For v3+, probe for maximum shared protocol version and max
request, response, and passthrough sizes. For now, this will
always fall back to v2, since there is no bus-specific code
for handling proto v3 packets.

Signed-off-by: Stephen Barber <smbarber@chromium.org>
Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Reviewed-by: Gwendal Grignou <gwendal@chromium.org>
Tested-by: Gwendal Grignou <gwendal@chromium.org>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Acked-by: Lee Jones <lee.jones@linaro.org>
Acked-by: Olof Johansson <olof@lixom.net>
---

Changes since v6:
- Add Olof Johansson Acked-by tag

Changes since v5: None

Changes since v4: None

Changes since v3:
- Added tested-by from Heiko Stuebner.
- Added acked-by tag from Lee Jones.

Changes since v2:
- Add the helpers to the drivers/platform/chrome/cros_ec_proto.c driver
instead of drivers/mfd/cros_ec.c. Suggested by Lee Jones.
- Rename the proto probe functions for proto_query since probe has a
special meaning in Linux so is confusing.

Changes since v1:
- Squash change https://chromium-review.googlesource.com/#/c/262870/ in
the patch. Suggested by Gwendal Grignou
- Add Reviewed-by and Tested-by tags from Gwendal Grignou
---
drivers/mfd/cros_ec.c | 23 ++-
drivers/mfd/cros_ec_i2c.c | 4 +
drivers/mfd/cros_ec_spi.c | 7 +-
drivers/platform/chrome/cros_ec_lpc.c | 4 +
drivers/platform/chrome/cros_ec_proto.c | 339 ++++++++++++++++++++++++++++----
include/linux/mfd/cros_ec.h | 28 ++-
6 files changed, 355 insertions(+), 50 deletions(-)

diff --git a/drivers/mfd/cros_ec.c b/drivers/mfd/cros_ec.c
index d857f6a2b57b..08d82bfc5268 100644
--- a/drivers/mfd/cros_ec.c
+++ b/drivers/mfd/cros_ec.c
@@ -36,19 +36,22 @@ int cros_ec_register(struct cros_ec_device *ec_dev)
struct device *dev = ec_dev->dev;
int err = 0;

- if (ec_dev->din_size) {
- ec_dev->din = devm_kzalloc(dev, ec_dev->din_size, GFP_KERNEL);
- if (!ec_dev->din)
- return -ENOMEM;
- }
- if (ec_dev->dout_size) {
- ec_dev->dout = devm_kzalloc(dev, ec_dev->dout_size, GFP_KERNEL);
- if (!ec_dev->dout)
- return -ENOMEM;
- }
+ ec_dev->max_request = sizeof(struct ec_params_hello);
+ ec_dev->max_response = sizeof(struct ec_response_get_protocol_info);
+ ec_dev->max_passthru = 0;
+
+ ec_dev->din = devm_kzalloc(dev, ec_dev->din_size, GFP_KERNEL);
+ if (!ec_dev->din)
+ return -ENOMEM;
+
+ ec_dev->dout = devm_kzalloc(dev, ec_dev->dout_size, GFP_KERNEL);
+ if (!ec_dev->dout)
+ return -ENOMEM;

mutex_init(&ec_dev->lock);

+ cros_ec_query_all(ec_dev);
+
err = mfd_add_devices(dev, 0, cros_devs,
ARRAY_SIZE(cros_devs),
NULL, ec_dev->irq, NULL);
diff --git a/drivers/mfd/cros_ec_i2c.c b/drivers/mfd/cros_ec_i2c.c
index fbf7819f5de5..b400bfa2772a 100644
--- a/drivers/mfd/cros_ec_i2c.c
+++ b/drivers/mfd/cros_ec_i2c.c
@@ -143,8 +143,12 @@ static int cros_ec_i2c_probe(struct i2c_client *client,
ec_dev->priv = client;
ec_dev->irq = client->irq;
ec_dev->cmd_xfer = cros_ec_cmd_xfer_i2c;
+ ec_dev->pkt_xfer = NULL;
ec_dev->ec_name = client->name;
ec_dev->phys_name = client->adapter->name;
+ ec_dev->din_size = sizeof(struct ec_host_response) +
+ sizeof(struct ec_response_get_protocol_info);
+ ec_dev->dout_size = sizeof(struct ec_host_request);

err = cros_ec_register(ec_dev);
if (err) {
diff --git a/drivers/mfd/cros_ec_spi.c b/drivers/mfd/cros_ec_spi.c
index 573730fec947..04da2f288ef8 100644
--- a/drivers/mfd/cros_ec_spi.c
+++ b/drivers/mfd/cros_ec_spi.c
@@ -361,10 +361,13 @@ static int cros_ec_spi_probe(struct spi_device *spi)
ec_dev->priv = ec_spi;
ec_dev->irq = spi->irq;
ec_dev->cmd_xfer = cros_ec_cmd_xfer_spi;
+ ec_dev->pkt_xfer = NULL;
ec_dev->ec_name = ec_spi->spi->modalias;
ec_dev->phys_name = dev_name(&ec_spi->spi->dev);
- ec_dev->din_size = EC_MSG_BYTES + EC_MSG_PREAMBLE_COUNT;
- ec_dev->dout_size = EC_MSG_BYTES;
+ 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);

err = cros_ec_register(ec_dev);
if (err) {
diff --git a/drivers/platform/chrome/cros_ec_lpc.c b/drivers/platform/chrome/cros_ec_lpc.c
index 214ae7fef984..06c5790b2c28 100644
--- a/drivers/platform/chrome/cros_ec_lpc.c
+++ b/drivers/platform/chrome/cros_ec_lpc.c
@@ -205,7 +205,11 @@ static int cros_ec_lpc_probe(struct platform_device *pdev)
ec_dev->ec_name = pdev->name;
ec_dev->phys_name = dev_name(dev);
ec_dev->cmd_xfer = cros_ec_cmd_xfer_lpc;
+ ec_dev->pkt_xfer = NULL;
ec_dev->cmd_readmem = cros_ec_lpc_readmem;
+ ec_dev->din_size = sizeof(struct ec_host_response) +
+ sizeof(struct ec_response_get_protocol_info);
+ ec_dev->dout_size = sizeof(struct ec_host_request);

ret = cros_ec_register(ec_dev);
if (ret) {
diff --git a/drivers/platform/chrome/cros_ec_proto.c b/drivers/platform/chrome/cros_ec_proto.c
index 58e98a24fd08..990308ca384f 100644
--- a/drivers/platform/chrome/cros_ec_proto.c
+++ b/drivers/platform/chrome/cros_ec_proto.c
@@ -22,11 +22,100 @@

#define EC_COMMAND_RETRIES 50

+static int prepare_packet(struct cros_ec_device *ec_dev,
+ struct cros_ec_command *msg)
+{
+ struct ec_host_request *request;
+ u8 *out;
+ int i;
+ u8 csum = 0;
+
+ BUG_ON(ec_dev->proto_version != EC_HOST_REQUEST_VERSION);
+ BUG_ON(msg->outsize + sizeof(*request) > ec_dev->dout_size);
+
+ out = ec_dev->dout;
+ request = (struct ec_host_request *)out;
+ request->struct_version = EC_HOST_REQUEST_VERSION;
+ request->checksum = 0;
+ request->command = msg->command;
+ request->command_version = msg->version;
+ request->reserved = 0;
+ request->data_len = msg->outsize;
+
+ for (i = 0; i < sizeof(*request); i++)
+ csum += out[i];
+
+ /* Copy data and update checksum */
+ memcpy(out + sizeof(*request), msg->data, msg->outsize);
+ for (i = 0; i < msg->outsize; i++)
+ csum += msg->data[i];
+
+ request->checksum = -csum;
+
+ return sizeof(*request) + msg->outsize;
+}
+
+static int send_command(struct cros_ec_device *ec_dev,
+ struct cros_ec_command *msg)
+{
+ int ret;
+
+ if (ec_dev->proto_version > 2)
+ ret = ec_dev->pkt_xfer(ec_dev, msg);
+ else
+ ret = ec_dev->cmd_xfer(ec_dev, msg);
+
+ if (msg->result == EC_RES_IN_PROGRESS) {
+ int i;
+ struct cros_ec_command *status_msg;
+ struct ec_response_get_comms_status *status;
+
+ status_msg = kmalloc(sizeof(*status_msg) + sizeof(*status),
+ GFP_KERNEL);
+ if (!status_msg)
+ return -ENOMEM;
+
+ status_msg->version = 0;
+ status_msg->command = EC_CMD_GET_COMMS_STATUS;
+ status_msg->insize = sizeof(*status);
+ status_msg->outsize = 0;
+
+ /*
+ * Query the EC's status until it's no longer busy or
+ * we encounter an error.
+ */
+ for (i = 0; i < EC_COMMAND_RETRIES; i++) {
+ usleep_range(10000, 11000);
+
+ ret = ec_dev->cmd_xfer(ec_dev, status_msg);
+ if (ret < 0)
+ break;
+
+ msg->result = status_msg->result;
+ if (status_msg->result != EC_RES_SUCCESS)
+ break;
+
+ status = (struct ec_response_get_comms_status *)
+ status_msg->data;
+ if (!(status->flags & EC_COMMS_STATUS_PROCESSING))
+ break;
+ }
+
+ kfree(status_msg);
+ }
+
+ return ret;
+}
+
int cros_ec_prepare_tx(struct cros_ec_device *ec_dev,
struct cros_ec_command *msg)
{
- uint8_t *out;
- int csum, i;
+ u8 *out;
+ u8 csum;
+ int i;
+
+ if (ec_dev->proto_version > 2)
+ return prepare_packet(ec_dev, msg);

BUG_ON(msg->outsize > EC_PROTO2_MAX_PARAM_SIZE);
out = ec_dev->dout;
@@ -36,7 +125,7 @@ int cros_ec_prepare_tx(struct cros_ec_device *ec_dev,
csum = out[0] + out[1] + out[2];
for (i = 0; i < msg->outsize; i++)
csum += out[EC_MSG_TX_HEADER_BYTES + i] = msg->data[i];
- out[EC_MSG_TX_HEADER_BYTES + msg->outsize] = (uint8_t)(csum & 0xff);
+ out[EC_MSG_TX_HEADER_BYTES + msg->outsize] = csum;

return EC_MSG_TX_PROTO_BYTES + msg->outsize;
}
@@ -60,54 +149,232 @@ int cros_ec_check_result(struct cros_ec_device *ec_dev,
}
EXPORT_SYMBOL(cros_ec_check_result);

-int cros_ec_cmd_xfer(struct cros_ec_device *ec_dev,
- struct cros_ec_command *msg)
+static int cros_ec_host_command_proto_query(struct cros_ec_device *ec_dev,
+ int devidx,
+ struct cros_ec_command *msg)
{
+ /*
+ * Try using v3+ to query for supported protocols. If this
+ * command fails, fall back to v2. Returns the highest protocol
+ * supported by the EC.
+ * Also sets the max request/response/passthru size.
+ */
int ret;

- mutex_lock(&ec_dev->lock);
- ret = ec_dev->cmd_xfer(ec_dev, msg);
- if (msg->result == EC_RES_IN_PROGRESS) {
- int i;
- struct cros_ec_command *status_msg;
- struct ec_response_get_comms_status *status;
+ if (!ec_dev->pkt_xfer)
+ return -EPROTONOSUPPORT;

- status_msg = kmalloc(sizeof(*status_msg) + sizeof(*status),
- GFP_KERNEL);
- if (!status_msg) {
- ret = -ENOMEM;
- goto exit;
- }
+ memset(msg, 0, sizeof(*msg));
+ msg->command = EC_CMD_PASSTHRU_OFFSET(devidx) | EC_CMD_GET_PROTOCOL_INFO;
+ msg->insize = sizeof(struct ec_response_get_protocol_info);

- status_msg->version = 0;
- status_msg->command = EC_CMD_GET_COMMS_STATUS;
- status_msg->insize = sizeof(*status);
- status_msg->outsize = 0;
+ ret = send_command(ec_dev, msg);
+
+ if (ret < 0) {
+ dev_dbg(ec_dev->dev,
+ "failed to check for EC[%d] protocol version: %d\n",
+ devidx, ret);
+ return ret;
+ }
+
+ if (devidx > 0 && msg->result == EC_RES_INVALID_COMMAND)
+ return -ENODEV;
+ else if (msg->result != EC_RES_SUCCESS)
+ return msg->result;
+
+ return 0;
+}
+
+static int cros_ec_host_command_proto_query_v2(struct cros_ec_device *ec_dev)
+{
+ struct cros_ec_command *msg;
+ struct ec_params_hello *hello_params;
+ struct ec_response_hello *hello_response;
+ int ret;
+ int len = max(sizeof(*hello_params), sizeof(*hello_response));
+
+ msg = kmalloc(sizeof(*msg) + len, GFP_KERNEL);
+ if (!msg)
+ return -ENOMEM;
+
+ msg->version = 0;
+ msg->command = EC_CMD_HELLO;
+ hello_params = (struct ec_params_hello *)msg->data;
+ msg->outsize = sizeof(*hello_params);
+ hello_response = (struct ec_response_hello *)msg->data;
+ msg->insize = sizeof(*hello_response);
+
+ hello_params->in_data = 0xa0b0c0d0;
+
+ ret = send_command(ec_dev, msg);
+
+ if (ret < 0) {
+ dev_dbg(ec_dev->dev,
+ "EC failed to respond to v2 hello: %d\n",
+ ret);
+ goto exit;
+ } else if (msg->result != EC_RES_SUCCESS) {
+ dev_err(ec_dev->dev,
+ "EC responded to v2 hello with error: %d\n",
+ msg->result);
+ ret = msg->result;
+ goto exit;
+ } else if (hello_response->out_data != 0xa1b2c3d4) {
+ dev_err(ec_dev->dev,
+ "EC responded to v2 hello with bad result: %u\n",
+ hello_response->out_data);
+ ret = -EBADMSG;
+ goto exit;
+ }
+
+ ret = 0;
+
+ exit:
+ kfree(msg);
+ return ret;
+}
+
+int cros_ec_query_all(struct cros_ec_device *ec_dev)
+{
+ struct device *dev = ec_dev->dev;
+ struct cros_ec_command *proto_msg;
+ struct ec_response_get_protocol_info *proto_info;
+ int ret;
+
+ proto_msg = kzalloc(sizeof(*proto_msg) + sizeof(*proto_info),
+ GFP_KERNEL);
+ if (!proto_msg)
+ return -ENOMEM;
+
+ /* First try sending with proto v3. */
+ ec_dev->proto_version = 3;
+ ret = cros_ec_host_command_proto_query(ec_dev, 0, proto_msg);
+
+ if (ret == 0) {
+ proto_info = (struct ec_response_get_protocol_info *)
+ proto_msg->data;
+ ec_dev->max_request = proto_info->max_request_packet_size -
+ sizeof(struct ec_host_request);
+ ec_dev->max_response = proto_info->max_response_packet_size -
+ sizeof(struct ec_host_response);
+ ec_dev->proto_version =
+ min(EC_HOST_REQUEST_VERSION,
+ fls(proto_info->protocol_versions) - 1);
+ dev_dbg(ec_dev->dev,
+ "using proto v%u\n",
+ ec_dev->proto_version);
+
+ ec_dev->din_size = ec_dev->max_response +
+ sizeof(struct ec_host_response) +
+ EC_MAX_RESPONSE_OVERHEAD;
+ ec_dev->dout_size = ec_dev->max_request +
+ sizeof(struct ec_host_request) +
+ EC_MAX_REQUEST_OVERHEAD;

/*
- * Query the EC's status until it's no longer busy or
- * we encounter an error.
+ * Check for PD
*/
- for (i = 0; i < EC_COMMAND_RETRIES; i++) {
- usleep_range(10000, 11000);
+ ret = cros_ec_host_command_proto_query(ec_dev, 1, proto_msg);

- ret = ec_dev->cmd_xfer(ec_dev, status_msg);
- if (ret < 0)
- break;
+ if (ret) {
+ dev_dbg(ec_dev->dev, "no PD chip found: %d\n", ret);
+ ec_dev->max_passthru = 0;
+ } else {
+ dev_dbg(ec_dev->dev, "found PD chip\n");
+ ec_dev->max_passthru =
+ proto_info->max_request_packet_size -
+ sizeof(struct ec_host_request);
+ }
+ } else {
+ /* Try querying with a v2 hello message. */
+ ec_dev->proto_version = 2;
+ ret = cros_ec_host_command_proto_query_v2(ec_dev);

- msg->result = status_msg->result;
- if (status_msg->result != EC_RES_SUCCESS)
- break;
+ if (ret == 0) {
+ /* V2 hello succeeded. */
+ dev_dbg(ec_dev->dev, "falling back to proto v2\n");

- status = (struct ec_response_get_comms_status *)
- status_msg->data;
- if (!(status->flags & EC_COMMS_STATUS_PROCESSING))
- break;
+ ec_dev->max_request = EC_PROTO2_MAX_PARAM_SIZE;
+ ec_dev->max_response = EC_PROTO2_MAX_PARAM_SIZE;
+ ec_dev->max_passthru = 0;
+ ec_dev->pkt_xfer = NULL;
+ ec_dev->din_size = EC_MSG_BYTES;
+ ec_dev->dout_size = EC_MSG_BYTES;
+ } else {
+ /*
+ * It's possible for a test to occur too early when
+ * the EC isn't listening. If this happens, we'll
+ * test later when the first command is run.
+ */
+ ec_dev->proto_version = EC_PROTO_VERSION_UNKNOWN;
+ dev_dbg(ec_dev->dev, "EC query failed: %d\n", ret);
+ goto exit;
}
+ }

- kfree(status_msg);
+ devm_kfree(dev, ec_dev->din);
+ devm_kfree(dev, ec_dev->dout);
+
+ ec_dev->din = devm_kzalloc(dev, ec_dev->din_size, GFP_KERNEL);
+ if (!ec_dev->din) {
+ ret = -ENOMEM;
+ goto exit;
}
+
+ ec_dev->dout = devm_kzalloc(dev, ec_dev->dout_size, GFP_KERNEL);
+ if (!ec_dev->dout) {
+ devm_kfree(dev, ec_dev->din);
+ ret = -ENOMEM;
+ goto exit;
+ }
+
exit:
+ kfree(proto_msg);
+ return ret;
+}
+EXPORT_SYMBOL(cros_ec_query_all);
+
+int cros_ec_cmd_xfer(struct cros_ec_device *ec_dev,
+ struct cros_ec_command *msg)
+{
+ int ret;
+
+ mutex_lock(&ec_dev->lock);
+ if (ec_dev->proto_version == EC_PROTO_VERSION_UNKNOWN) {
+ ret = cros_ec_query_all(ec_dev);
+ if (ret) {
+ dev_err(ec_dev->dev,
+ "EC version unknown and query failed; aborting command\n");
+ mutex_unlock(&ec_dev->lock);
+ return ret;
+ }
+ }
+
+ if (msg->insize > ec_dev->max_response) {
+ dev_dbg(ec_dev->dev, "clamping message receive buffer\n");
+ msg->insize = ec_dev->max_response;
+ }
+
+ if (msg->command < EC_CMD_PASSTHRU_OFFSET(1)) {
+ if (msg->outsize > ec_dev->max_request) {
+ dev_err(ec_dev->dev,
+ "request of size %u is too big (max: %u)\n",
+ msg->outsize,
+ ec_dev->max_request);
+ mutex_unlock(&ec_dev->lock);
+ return -EMSGSIZE;
+ }
+ } else {
+ if (msg->outsize > ec_dev->max_passthru) {
+ dev_err(ec_dev->dev,
+ "passthru rq of size %u is too big (max: %u)\n",
+ msg->outsize,
+ ec_dev->max_passthru);
+ mutex_unlock(&ec_dev->lock);
+ return -EMSGSIZE;
+ }
+ }
+ ret = send_command(ec_dev, msg);
mutex_unlock(&ec_dev->lock);

return ret;
diff --git a/include/linux/mfd/cros_ec.h b/include/linux/mfd/cros_ec.h
index 7eee38abd02a..59d909434efd 100644
--- a/include/linux/mfd/cros_ec.h
+++ b/include/linux/mfd/cros_ec.h
@@ -22,6 +22,15 @@
#include <linux/mutex.h>

/*
+ * Max bus-specific overhead incurred by request/responses.
+ * I2C requires 1 additional byte for requests.
+ * I2C requires 2 additional bytes for responses.
+ * */
+#define EC_PROTO_VERSION_UNKNOWN 0
+#define EC_MAX_REQUEST_OVERHEAD 1
+#define EC_MAX_RESPONSE_OVERHEAD 2
+
+/*
* Command interface between EC and AP, for LPC, I2C and SPI interfaces.
*/
enum {
@@ -88,6 +97,7 @@ struct cros_ec_command {
* Returns the number of bytes received if the communication succeeded, but
* that doesn't mean the EC was happy with the command. The caller
* should check msg.result for the EC's result code.
+ * @pkt_xfer: send packet to EC and get response
* @lock: one transaction at a time
*/
struct cros_ec_device {
@@ -104,15 +114,21 @@ struct cros_ec_device {
unsigned int bytes, void *dest);

/* These are used to implement the platform-specific interface */
+ u16 max_request;
+ u16 max_response;
+ u16 max_passthru;
+ u16 proto_version;
void *priv;
int irq;
- uint8_t *din;
- uint8_t *dout;
+ u8 *din;
+ u8 *dout;
int din_size;
int dout_size;
bool wake_enabled;
int (*cmd_xfer)(struct cros_ec_device *ec,
struct cros_ec_command *msg);
+ int (*pkt_xfer)(struct cros_ec_device *ec,
+ struct cros_ec_command *msg);
struct mutex lock;
};

@@ -194,4 +210,12 @@ int cros_ec_remove(struct cros_ec_device *ec_dev);
*/
int cros_ec_register(struct cros_ec_device *ec_dev);

+/**
+ * cros_ec_register - Query the protocol version supported by the ChromeOS EC
+ *
+ * @ec_dev: Device to register
+ * @return 0 if ok, -ve on error
+ */
+int cros_ec_query_all(struct cros_ec_device *ec_dev);
+
#endif /* __LINUX_MFD_CROS_EC_H */
--
2.1.4