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* [PATCH 1/2] cros: platform/chrome: Add cros-ec-uart driver for uart support
@ 2020-06-25 21:34 Bhanu Prakash Maiya
  2020-06-25 21:34 ` [PATCH 2/2] dt-bindings: mfd: Add DT compatible string "google,cros_ec_uart" Bhanu Prakash Maiya
                   ` (2 more replies)
  0 siblings, 3 replies; 7+ messages in thread
From: Bhanu Prakash Maiya @ 2020-06-25 21:34 UTC (permalink / raw)
  To: linux-arm-kernel
  Cc: Benson Leung, Enric Balletbo i Serra, Guenter Roeck,
	linux-kernel, Lee Jones ),
	Rob Herring, Raul E Rangel, Furquan Shaikh, Duncan Laurie,
	Eric Peers, devicetree, Bhanu Prakash Maiya

This patch enables uart transport layer for cros_ec framework.
The cros-ec-uart binds with EC device working on uart transport to
send request and receive response.

Signed-off-by: Bhanu Prakash Maiya <bhanumaiya@google.com>
---

 MAINTAINERS                            |   1 +
 drivers/platform/chrome/Kconfig        |  10 +
 drivers/platform/chrome/Makefile       |   1 +
 drivers/platform/chrome/cros_ec_uart.c | 399 +++++++++++++++++++++++++
 4 files changed, 411 insertions(+)
 create mode 100644 drivers/platform/chrome/cros_ec_uart.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 7b5ffd646c6b9..d4a089673429a 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -4095,6 +4095,7 @@ F:	sound/soc/codecs/cros_ec_codec.*
 CHROMEOS EC SUBDRIVERS
 M:	Benson Leung <bleung@chromium.org>
 M:	Enric Balletbo i Serra <enric.balletbo@collabora.com>
+M:	Bhanu Prakash Maiya <bhanumaiya@chromium.org>
 R:	Guenter Roeck <groeck@chromium.org>
 S:	Maintained
 F:	drivers/power/supply/cros_usbpd-charger.c
diff --git a/drivers/platform/chrome/Kconfig b/drivers/platform/chrome/Kconfig
index cf072153bdc5d..88b1b7b277ba3 100644
--- a/drivers/platform/chrome/Kconfig
+++ b/drivers/platform/chrome/Kconfig
@@ -118,6 +118,16 @@ config CROS_EC_SPI
 	  response time cannot be guaranteed, we support ignoring
 	  'pre-amble' bytes before the response actually starts.
 
+config CROS_EC_UART
+	tristate "ChromeOS Embedded Controller (UART)"
+	depends on CROS_EC && ACPI && SERIAL_DEV_BUS
+	help
+	  If you say Y here, you get support for talking to the ChromeOS EC
+	  through a UART, using a byte-level protocol.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called cros_ec_uart.
+
 config CROS_EC_LPC
 	tristate "ChromeOS Embedded Controller (LPC)"
 	depends on CROS_EC && ACPI && (X86 || COMPILE_TEST)
diff --git a/drivers/platform/chrome/Makefile b/drivers/platform/chrome/Makefile
index 41baccba033f7..47d8d0f890ca2 100644
--- a/drivers/platform/chrome/Makefile
+++ b/drivers/platform/chrome/Makefile
@@ -11,6 +11,7 @@ obj-$(CONFIG_CROS_EC_I2C)		+= cros_ec_i2c.o
 obj-$(CONFIG_CROS_EC_ISHTP)		+= cros_ec_ishtp.o
 obj-$(CONFIG_CROS_EC_RPMSG)		+= cros_ec_rpmsg.o
 obj-$(CONFIG_CROS_EC_SPI)		+= cros_ec_spi.o
+obj-$(CONFIG_CROS_EC_UART)		+= cros_ec_uart.o
 cros_ec_lpcs-objs			:= cros_ec_lpc.o cros_ec_lpc_mec.o
 obj-$(CONFIG_CROS_EC_TYPEC)		+= cros_ec_typec.o
 obj-$(CONFIG_CROS_EC_LPC)		+= cros_ec_lpcs.o
diff --git a/drivers/platform/chrome/cros_ec_uart.c b/drivers/platform/chrome/cros_ec_uart.c
new file mode 100644
index 0000000000000..fe17c2a28b6ef
--- /dev/null
+++ b/drivers/platform/chrome/cros_ec_uart.c
@@ -0,0 +1,399 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * UART interface for ChromeOS Embedded Controller
+ *
+ * Copyright 2020 Google LLC.
+ */
+
+#include <linux/delay.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/acpi.h>
+#include <linux/of.h>
+#include <linux/platform_data/cros_ec_commands.h>
+#include <linux/platform_data/cros_ec_proto.h>
+#include <linux/platform_device.h>
+#include <linux/serdev.h>
+#include <linux/slab.h>
+#include <uapi/linux/sched/types.h>
+
+/*
+ * Allow for a long time for EC to respond.
+ */
+#define EC_MSG_DEADLINE_MS		200
+
+/**
+ * struct response_info - Encapsulate EC response related
+ *			information for passing between function
+ *			cros_ec_uart_pkt_xfer() and cros_ec_uart_rx_bytes()
+ *			callback.
+ * @data:		Copy the data received from EC here.
+ * @max_size:		Max size allocated for the @data buffer. If the
+ *			received data exceeds this value, we log an error.
+ * @size:		Actual size of data received from EC. This is also
+ *			used to accumulate byte count with response is received
+ *			in dma chunks.
+ * @exp_len:		Expected bytes of response from EC.
+ * @error:		0 for success, negative error code for a failure.
+ * @received:		Set to true on receiving a valid EC response.
+ * @wait_queue:		Wait queue EC response where the cros_ec sends request
+ *			to EC and waits
+ */
+struct response_info {
+	void *data;
+	size_t max_size;
+	size_t size;
+	int error;
+	size_t exp_len;
+	bool received;
+	wait_queue_head_t wait_queue;
+};
+
+/**
+ * struct cros_ec_uart - information about a uart-connected EC
+ *
+ * @serdev_device:	serdev uart device we are connected to.
+ * @baudrate:		UART baudrate of attached EC device.
+ * @flowcontrol:	UART flowcontrol of attached device.
+ * @irq:		Linux IRQ number of associated serial device.
+ * @response:		Response info passing between cros_ec_uart_pkt_xfer()
+ *			and cros_ec_uart_rx_bytes()
+ */
+struct cros_ec_uart {
+	struct serdev_device *serdev;
+	u32 baudrate;
+	u8  flowcontrol;
+	u32 irq;
+	struct response_info response;
+};
+
+static int cros_ec_uart_rx_bytes(struct serdev_device *serdev,
+				 const u8 *data,
+				 size_t count)
+{
+	struct ec_host_response *response;
+	struct cros_ec_device *ec_dev =   serdev_device_get_drvdata(serdev);
+	struct cros_ec_uart *ec_uart = ec_dev->priv;
+
+	/* Check if bytes were sent out of band */
+	if (!ec_uart->response.data) {
+		/* Discard all bytes */
+		return count;
+	}
+
+	/*
+	 * Check if incoming bytes + response.size are less than allocated
+	 * buffer in din by cros_ec. This will ensure that if EC sends more
+	 * bytes than max_size, waiting process will be notified with an error.
+	 */
+	if (ec_uart->response.size + count <= ec_uart->response.max_size) {
+		/* Copy bytes in data in buffer */
+		memcpy((void *)ec_uart->response.data + ec_uart->response.size,
+		       (void *)data, count);
+
+		/* Add incoming bytes in size */
+		ec_uart->response.size += count;
+
+		/*
+		 * Read data_len if we received response header and if exp_len
+		 * was not read before.
+		 */
+		if (ec_uart->response.size >= sizeof(*response) &&
+		    ec_uart->response.exp_len == 0) {
+			/* Get expected response length from response header */
+			response = (struct ec_host_response *)
+							ec_uart->response.data;
+
+			ec_uart->response.exp_len = response->data_len +
+				sizeof(*response);
+		}
+
+		/* Check if we received all response bytes from EC */
+		if (ec_uart->response.size >= ec_uart->response.exp_len) {
+			/* Set flag before waking up the caller */
+			ec_uart->response.received = true;
+
+			/* Wake the calling thread */
+			wake_up_interruptible(&ec_uart->response.wait_queue);
+		}
+	} else {
+		/* Received bytes are more the allocated buffer*/
+		ec_uart->response.error = -EMSGSIZE;
+
+		/* Wake the calling thread */
+		wake_up_interruptible(&ec_uart->response.wait_queue);
+	}
+
+	return count;
+}
+
+static int cros_ec_uart_pkt_xfer(struct cros_ec_device *ec_dev,
+				 struct cros_ec_command *ec_msg)
+{
+	struct cros_ec_uart *ec_uart = ec_dev->priv;
+	struct serdev_device *serdev = ec_uart->serdev;
+	struct ec_host_response *response;
+	unsigned int len;
+	int ret, i;
+	u8 sum = 0;
+
+	/* Prepare an outgoing message in the output buffer */
+	len = cros_ec_prepare_tx(ec_dev, ec_msg);
+	dev_dbg(ec_dev->dev, "Prepared len=%d\n", len);
+
+	/* Setup for incoming response */
+	ec_uart->response.data = ec_dev->din;
+	ec_uart->response.max_size = ec_dev->din_size;
+	ec_uart->response.size = 0;
+	ec_uart->response.error = 0;
+	ec_uart->response.exp_len = 0;
+	ec_uart->response.received = false;
+
+	/* Write serial device buffer */
+	ret = serdev_device_write_buf(serdev, ec_dev->dout, len);
+	if (ret < len) {
+		dev_err(&serdev->dev,
+			"Unable to write data to serial device %s",
+			dev_name(&serdev->dev));
+
+		/* Return EIO as controller had issues writing buffer */
+		ret = -EIO;
+		goto exit;
+	}
+
+	/* Once request is successfully sent to EC, wait to wait_queue */
+	wait_event_interruptible_timeout(ec_uart->response.wait_queue,
+					 ec_uart->response.received,
+					 msecs_to_jiffies(EC_MSG_DEADLINE_MS));
+
+	/* Check if wait_queue was interrupted due to an error */
+	if (ec_uart->response.error < 0) {
+		dev_warn(&serdev->dev, "Response error detected.\n");
+
+		ret = ec_uart->response.error;
+		goto exit;
+	}
+
+	/* Check if valid response was received or there was a timeout */
+	if (!ec_uart->response.received) {
+		dev_warn(&serdev->dev, "EC failed to respond in time.\n");
+
+		ret = -ETIMEDOUT;
+		goto exit;
+	}
+
+	/* Check response error code */
+	response = (struct ec_host_response *)ec_dev->din;
+	ec_msg->result = response->result;
+
+	/* Check if received response is longer than expected */
+	if (response->data_len > ec_msg->insize) {
+		dev_err(ec_dev->dev, "Resp too long (%d bytes, expected %d)",
+			response->data_len,
+			ec_msg->insize);
+		ret = -ENOSPC;
+		goto exit;
+	}
+
+	/* Copy response packet to ec_msg data buffer */
+	memcpy(ec_msg->data,
+	       ec_dev->din + sizeof(*response),
+	       response->data_len);
+
+	/* Add all response header bytes for checksum calculation */
+	for (i = 0; i < sizeof(*response); i++)
+		sum += ec_dev->din[i];
+
+	/* Copy response packet payload and compute checksum */
+	for (i = 0; i < response->data_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;
+	}
+
+	/* Return data_len to cros_ec */
+	ret = response->data_len;
+
+exit:
+	/* Reset ec_uart */
+	ec_uart->response.data = NULL;
+	ec_uart->response.max_size = 0;
+	ec_uart->response.size = 0;
+	ec_uart->response.error = 0;
+	ec_uart->response.exp_len = 0;
+	ec_uart->response.received = false;
+
+	if (ec_msg->command == EC_CMD_REBOOT_EC)
+		msleep(EC_REBOOT_DELAY_MS);
+
+	return ret;
+}
+
+static int cros_ec_uart_resource(struct acpi_resource *ares, void *data)
+{
+	struct cros_ec_uart *ec_uart = data;
+	struct acpi_resource_uart_serialbus *sb;
+
+	switch (ares->type) {
+	case ACPI_RESOURCE_TYPE_SERIAL_BUS:
+		sb = &ares->data.uart_serial_bus;
+		if (sb->type == ACPI_RESOURCE_SERIAL_TYPE_UART) {
+			ec_uart->baudrate = sb->default_baud_rate;
+			dev_dbg(&ec_uart->serdev->dev, "Baudrate %d\n",
+				ec_uart->baudrate);
+
+			ec_uart->flowcontrol = sb->flow_control;
+			dev_dbg(&ec_uart->serdev->dev, "Flow control %d\n",
+				ec_uart->flowcontrol);
+		}
+		break;
+	default:
+		break;
+	}
+
+	return 0;
+}
+
+static int cros_ec_uart_acpi_probe(struct cros_ec_uart *ec_uart)
+{
+	LIST_HEAD(resources);
+	struct acpi_device *adev = ACPI_COMPANION(&ec_uart->serdev->dev);
+	int ret;
+
+	/* Retrieve UART ACPI info */
+	ret = acpi_dev_get_resources(adev, &resources,
+				     cros_ec_uart_resource, ec_uart);
+	if (ret < 0)
+		return ret;
+
+	acpi_dev_free_resource_list(&resources);
+
+	/* Retrieve GpioInt and translate it to Linux IRQ number */
+	ret = acpi_dev_gpio_irq_get(adev, 0);
+	if (ret < 0)
+		return ret;
+
+	ec_uart->irq = ret;
+	dev_dbg(&ec_uart->serdev->dev, "IRQ number %d\n", ec_uart->irq);
+
+	return 0;
+}
+
+static const struct serdev_device_ops cros_ec_uart_client_ops = {
+	.receive_buf = cros_ec_uart_rx_bytes,
+};
+
+static int cros_ec_uart_probe(struct serdev_device *serdev)
+{
+	struct device *dev = &serdev->dev;
+	struct cros_ec_device *ec_dev;
+	struct cros_ec_uart *ec_uart;
+	int ret;
+
+	ec_uart = devm_kzalloc(dev, sizeof(*ec_uart), GFP_KERNEL);
+	if (!ec_uart)
+		return -ENOMEM;
+
+	ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL);
+	if (!ec_dev)
+		return -ENOMEM;
+
+	ec_uart->serdev = serdev;
+
+	/* Open the serial device */
+	ret = devm_serdev_device_open(dev, ec_uart->serdev);
+	if (ret) {
+		dev_err(dev, "Unable to open UART device %s",
+			dev_name(&serdev->dev));
+		return ret;
+	}
+
+	serdev_device_set_drvdata(serdev, ec_dev);
+
+	serdev_device_set_client_ops(serdev, &cros_ec_uart_client_ops);
+
+	/* Initialize wait queue */
+	init_waitqueue_head(&ec_uart->response.wait_queue);
+
+	ret = cros_ec_uart_acpi_probe(ec_uart);
+	if (ret < 0) {
+		dev_err(dev, "Failed to get ACPI info (%d)", ret);
+		return ret;
+	}
+
+	/* Set baud rate of serial device */
+	ret = serdev_device_set_baudrate(serdev, ec_uart->baudrate);
+	if (ret < 0) {
+		dev_err(dev, "Failed to set up host baud rate (%d)", ret);
+		return ret;
+	}
+
+	/* Set flow control of serial device */
+	serdev_device_set_flow_control(serdev, ec_uart->flowcontrol);
+
+	/* Initialize ec_dev for cros_ec  */
+	ec_dev->phys_name = dev_name(&ec_uart->serdev->dev);
+	ec_dev->dev = dev;
+	ec_dev->priv = ec_uart;
+	ec_dev->irq = ec_uart->irq;
+	ec_dev->cmd_xfer = NULL;
+	ec_dev->pkt_xfer = cros_ec_uart_pkt_xfer;
+	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);
+
+	/* Register a new cros_ec device */
+	return cros_ec_register(ec_dev);
+}
+
+static void cros_ec_uart_remove(struct serdev_device *serdev)
+{
+	struct cros_ec_device *ec_dev = serdev_device_get_drvdata(serdev);
+
+	cros_ec_unregister(ec_dev);
+};
+
+static int __maybe_unused cros_ec_uart_suspend(struct device *dev)
+{
+	struct cros_ec_device *ec_dev = dev_get_drvdata(dev);
+
+	return cros_ec_suspend(ec_dev);
+}
+
+static int __maybe_unused cros_ec_uart_resume(struct device *dev)
+{
+	struct cros_ec_device *ec_dev = dev_get_drvdata(dev);
+
+	return cros_ec_resume(ec_dev);
+}
+
+static SIMPLE_DEV_PM_OPS(cros_ec_uart_pm_ops, cros_ec_uart_suspend,
+			 cros_ec_uart_resume);
+
+static const struct of_device_id cros_ec_uart_of_match[] = {
+	{ .compatible = "google,cros-ec-uart" },
+	{}
+};
+
+static struct serdev_device_driver cros_ec_uart_driver = {
+	.driver	= {
+		.name	= "cros-ec-uart",
+		.of_match_table = cros_ec_uart_of_match,
+		.pm	= &cros_ec_uart_pm_ops,
+	},
+	.probe		= cros_ec_uart_probe,
+	.remove		= cros_ec_uart_remove,
+};
+
+module_serdev_device_driver(cros_ec_uart_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("UART interface for ChromeOS Embedded Controller");
+MODULE_AUTHOR("Bhanu Prakash Maiya <bhanumaiya@chromium.org>");
-- 
2.26.2


^ permalink raw reply related	[flat|nested] 7+ messages in thread
* [PATCH 2/2] dt-bindings: mfd: Add DT compatible string "google,cros_ec_uart"
@ 2020-07-15  7:41 Bhanu Prakash Maiya
  2020-07-15  7:56 ` Greg Kroah-Hartman
  0 siblings, 1 reply; 7+ messages in thread
From: Bhanu Prakash Maiya @ 2020-07-15  7:41 UTC (permalink / raw)
  To: linux-arm-kernel
  Cc: Lee Jones, Furquan Shaikh, Raul E Rangel, Eric Peers,
	Duncan Laurie, Benson Leung, Enric Balletbo i Serra,
	Bhanu Prakash Maiya, Guenter Roeck, Mauro Carvalho Chehab,
	David S . Miller, Rob Herring, Greg Kroah-Hartman, devicetree,
	linux-kernel

From: Bhanu Prakash Maiya <bhanumaiya@chromium.org>

Add DT compatible string in
Documentation/devicetree/bindings/mfd/cros_ec.txt

Series-to: LKML <linux-kernel@vger.kernel.org>
Series-cc: Raul E Rangel <rrangel@chromium.org>, Furquan Shaikh <furquan@chromium.org>, Duncan Laurie <dlaurie@google.com>, Eric Peers <epeers@google.com>, Benson Leung <bleung@chromium.org>, Enric Balletbo i Serra <enric.balletbo@collabora.com>, Guenter Roeck <groeck@chromium.org>, linux-kernel@vger.kernel.org, Lee Jones <lee.jones@linaro.org>, Rob Herring <robh+dt@kernel.org>, devicetree@vger.kernel.org

Signed-off-by: Bhanu Prakash Maiya <bhanumaiya@chromium.org>
Change-Id: Icfeab15fa04daaffc61280faf5a75cd9b23ee822
---
 Documentation/devicetree/bindings/mfd/cros-ec.txt | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/mfd/cros-ec.txt b/Documentation/devicetree/bindings/mfd/cros-ec.txt
index 4860eabd0f729..ec8c5d7ecc266 100644
--- a/Documentation/devicetree/bindings/mfd/cros-ec.txt
+++ b/Documentation/devicetree/bindings/mfd/cros-ec.txt
@@ -3,7 +3,7 @@ ChromeOS Embedded Controller
 Google's ChromeOS EC is a Cortex-M device which talks to the AP and
 implements various function such as keyboard and battery charging.
 
-The EC can be connect through various means (I2C, SPI, LPC, RPMSG) and the
+The EC can be connect through various means (I2C, SPI, UART, LPC, RPMSG) and the
 compatible string used depends on the interface. Each connection method has
 its own driver which connects to the top level interface-agnostic EC driver.
 Other Linux driver (such as cros-ec-keyb for the matrix keyboard) connect to
@@ -17,6 +17,10 @@ Required properties (SPI):
 - compatible: "google,cros-ec-spi"
 - reg: SPI chip select
 
+Required properties (UART):
+- compatible: "google,cros-ec-uart"
+- reg: UART baudrate, flowcontrol
+
 Required properties (RPMSG):
 - compatible: "google,cros-ec-rpmsg"
 
@@ -72,5 +76,6 @@ spi@131b0000 {
 	};
 };
 
-
 Example for LPC is not supplied as it is not yet implemented.
+
+Example for UART is not supplied as it is not yet implemented.
-- 
2.26.2


^ permalink raw reply related	[flat|nested] 7+ messages in thread
end of thread, other threads:[~2020-07-15  7:56 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-06-25 21:34 [PATCH 1/2] cros: platform/chrome: Add cros-ec-uart driver for uart support Bhanu Prakash Maiya
2020-06-25 21:34 ` [PATCH 2/2] dt-bindings: mfd: Add DT compatible string "google,cros_ec_uart" Bhanu Prakash Maiya
2020-06-26  8:42   ` Enric Balletbo i Serra
2020-06-26  0:18 ` [PATCH 1/2] cros: platform/chrome: Add cros-ec-uart driver for uart support kernel test robot
2020-06-26  8:33 ` kernel test robot
2020-07-15  7:41 [PATCH 2/2] dt-bindings: mfd: Add DT compatible string "google,cros_ec_uart" Bhanu Prakash Maiya
2020-07-15  7:56 ` Greg Kroah-Hartman

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