diff --git a/MAINTAINERS b/MAINTAINERS index f61eb221415b..49b0f0525502 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -4985,6 +4985,13 @@ S: Maintained F: Documentation/devicetree/bindings/sound/google,cros-ec-codec.yaml F: sound/soc/codecs/cros_ec_codec.* +CHROMEOS EC UART DRIVER +M: Bhanu Prakash Maiya <bhanumaiya@chromium.org> +R: Benson Leung <bleung@chromium.org> +R: Tzung-Bi Shih <tzungbi@kernel.org> +S: Maintained +F: drivers/platform/chrome/cros_ec_uart.c + CHROMEOS EC SUBDRIVERS M: Benson Leung <bleung@chromium.org> R: Guenter Roeck <groeck@chromium.org> diff --git a/drivers/platform/chrome/Kconfig b/drivers/platform/chrome/Kconfig index c1ca247987d2..0d272c87f32b 100644 --- a/drivers/platform/chrome/Kconfig +++ b/drivers/platform/chrome/Kconfig @@ -119,6 +119,16 @@ 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 f6068d077a40..0f39edef660d 100644 --- a/drivers/platform/chrome/Makefile +++ b/drivers/platform/chrome/Makefile @@ -15,6 +15,7 @@ obj-$(CONFIG_CROS_EC_ISHTP) += cros_ec_ishtp.o obj-$(CONFIG_CROS_TYPEC_SWITCH) += cros_typec_switch.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 000000000000..971ea4bc2df8 --- /dev/null +++ b/drivers/platform/chrome/cros_ec_uart.c @@ -0,0 +1,352 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * UART interface for ChromeOS Embedded Controller + * + * Copyright 2020-2022 Google LLC. + */ + +#include <linux/acpi.h> +#include <linux/delay.h> +#include <linux/errno.h> +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/platform_data/cros_ec_proto.h> +#include <linux/serdev.h> +#include <linux/slab.h> +#include <uapi/linux/sched/types.h> + +#include "cros_ec.h" + +/* + * EC sends contiguous bytes of response packet on UART AP RX. + * TTY driver in AP accumulates incoming bytes and calls the registered callback + * function. Byte count can range from 1 to MAX bytes supported by EC. + * This driver should wait for long time for all callbacks to be processed. + * Considering the worst case scenario, wait for 500 msec. This timeout should + * account for max latency and some additional guard time. + * Best case: Entire packet is received in ~200 ms, wait queue will be released + * and packet will be processed. + * Worst case: TTY driver sends bytes in multiple callbacks. In this case this + * driver will wait for ~1 sec beyond which it will timeout. + * This timeout value should not exceed ~500 msec because in case if + * EC_CMD_REBOOT_EC sent, high level driver should be able to intercept EC + * in RO. + */ +#define EC_MSG_DEADLINE_MS 500 + +/** + * 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 including header. + * @status: Re-init to 0 before sending a cmd. Updated to 1 when + * a response is successfully received, or an error number + * on failure. + * @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; + size_t exp_len; + int status; + wait_queue_head_t wait_queue; +}; + +/** + * struct cros_ec_uart - information about a uart-connected EC + * + * @serdev: 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 *host_response; + struct cros_ec_device *ec_dev = serdev_device_get_drvdata(serdev); + struct cros_ec_uart *ec_uart = ec_dev->priv; + struct response_info *resp = &ec_uart->response; + + /* Check if bytes were sent out of band */ + if (!resp->data) { + /* Discard all bytes */ + dev_warn(ec_dev->dev, "Bytes received out of band, dropping them.\n"); + return count; + } + + /* + * Check if incoming bytes + resp->size is greater 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 (resp->size + count > resp->max_size) { + resp->status = -EMSGSIZE; + wake_up(&resp->wait_queue); + return count; + } + + memcpy(resp->data + resp->size, data, count); + + resp->size += count; + + /* Read data_len if we received response header and if exp_len was not read before. */ + if (resp->size >= sizeof(*host_response) && resp->exp_len == 0) { + host_response = (struct ec_host_response *)resp->data; + resp->exp_len = host_response->data_len + sizeof(*host_response); + } + + /* If driver received response header and payload from EC, wake up the wait queue. */ + if (resp->size >= sizeof(*host_response) && resp->size == resp->exp_len) { + resp->status = 1; + wake_up(&resp->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 response_info *resp = &ec_uart->response; + struct ec_host_response *host_response; + unsigned int len; + int ret, i; + u8 sum; + + len = cros_ec_prepare_tx(ec_dev, ec_msg); + dev_dbg(ec_dev->dev, "Prepared len=%d\n", len); + + /* Setup for incoming response */ + resp->data = ec_dev->din; + resp->max_size = ec_dev->din_size; + resp->size = 0; + resp->exp_len = 0; + resp->status = 0; + + ret = serdev_device_write_buf(serdev, ec_dev->dout, len); + if (ret < len) { + dev_err(ec_dev->dev, "Unable to write data\n"); + ret = -EIO; + goto exit; + } + + ret = wait_event_timeout(resp->wait_queue, resp->status, + msecs_to_jiffies(EC_MSG_DEADLINE_MS)); + if (ret == 0) { + dev_warn(ec_dev->dev, "Timed out waiting for response.\n"); + ret = -ETIMEDOUT; + goto exit; + } + + if (resp->status < 0) { + ret = resp->status; + dev_warn(ec_dev->dev, "Error response received: %d\n", ret); + goto exit; + } + + host_response = (struct ec_host_response *)ec_dev->din; + ec_msg->result = host_response->result; + + if (host_response->data_len > ec_msg->insize) { + dev_err(ec_dev->dev, "Resp too long (%d bytes, expected %d)\n", + host_response->data_len, ec_msg->insize); + ret = -ENOSPC; + goto exit; + } + + /* Validate checksum */ + sum = 0; + for (i = 0; i < sizeof(*host_response) + host_response->data_len; i++) + sum += ec_dev->din[i]; + + if (sum) { + dev_err(ec_dev->dev, "Bad packet checksum calculated %x\n", sum); + ret = -EBADMSG; + goto exit; + } + + memcpy(ec_msg->data, ec_dev->din + sizeof(*host_response), host_response->data_len); + + ret = host_response->data_len; + +exit: + /* Invalidate response buffer to guard against out of band rx data */ + resp->data = NULL; + + 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 = &ares->data.uart_serial_bus; + + if (ares->type == ACPI_RESOURCE_TYPE_SERIAL_BUS && + 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); + } + + return 0; +} + +static int cros_ec_uart_acpi_probe(struct cros_ec_uart *ec_uart) +{ + int ret; + LIST_HEAD(resources); + struct acpi_device *adev = ACPI_COMPANION(&ec_uart->serdev->dev); + + 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; + + ret = devm_serdev_device_open(dev, serdev); + if (ret) { + dev_err(dev, "Unable to open UART device"); + return ret; + } + + serdev_device_set_drvdata(serdev, ec_dev); + serdev_device_set_client_ops(serdev, &cros_ec_uart_client_ops); + init_waitqueue_head(&ec_uart->response.wait_queue); + + ec_uart->serdev = serdev; + + ret = cros_ec_uart_acpi_probe(ec_uart); + if (ret < 0) { + dev_err(dev, "Failed to get ACPI info (%d)", ret); + return ret; + } + + 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; + } + + serdev_device_set_flow_control(serdev, ec_uart->flowcontrol); + + /* Initialize ec_dev for cros_ec */ + ec_dev->phys_name = dev_name(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); + + 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); + +#ifdef CONFIG_ACPI +static const struct acpi_device_id cros_ec_uart_acpi_id[] = { + { "GOOG0019", 0 }, + {} +}; + +MODULE_DEVICE_TABLE(acpi, cros_ec_uart_acpi_id); +#endif + +static struct serdev_device_driver cros_ec_uart_driver = { + .driver = { + .name = "cros-ec-uart", + .acpi_match_table = ACPI_PTR(cros_ec_uart_acpi_id), + .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"); +MODULE_DESCRIPTION("UART interface for ChromeOS Embedded Controller"); +MODULE_AUTHOR("Bhanu Prakash Maiya <bhanumaiya@chromium.org>");