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Date: Tue, 4 Jan 2022 21:12:42 -0600 From: "Dustin L. Howett" <dustin@...ett.net> To: linux-kernel@...r.kernel.org Cc: Benson Leung <bleung@...omium.org>, Guenter Roeck <groeck@...omium.org>, "Dustin L. Howett" <dustin@...ett.net> Subject: [PATCH 2/2] platform/chrome: reserve only the I/O ports required for the MEC EC Some ChromeOS EC devices (such as the Framework Laptop) only map I/O ports 0x800-0x807. Making the larger reservation required by the non-MEC LPC (the 0xFF ports for the memory map, and the 0xFF ports for the parameter region) is non-viable on these devices. Since we probe the MEC EC first, we can get away with a smaller reservation that covers the MEC EC ports. If we fall back to classic LPC, we can grow the reservation to cover the memory map and the parameter region. Signed-off-by: Dustin L. Howett <dustin@...ett.net> --- drivers/platform/chrome/cros_ec_lpc.c | 39 ++++++++++++------- .../linux/platform_data/cros_ec_commands.h | 4 ++ 2 files changed, 30 insertions(+), 13 deletions(-) diff --git a/drivers/platform/chrome/cros_ec_lpc.c b/drivers/platform/chrome/cros_ec_lpc.c index 458eb59db2ff..06fdfe365710 100644 --- a/drivers/platform/chrome/cros_ec_lpc.c +++ b/drivers/platform/chrome/cros_ec_lpc.c @@ -341,9 +341,14 @@ static int cros_ec_lpc_probe(struct platform_device *pdev) u8 buf[2]; int irq, ret; - if (!devm_request_region(dev, EC_LPC_ADDR_MEMMAP, EC_MEMMAP_SIZE, - dev_name(dev))) { - dev_err(dev, "couldn't reserve memmap region\n"); + /* + * The Framework Laptop (and possibly other non-ChromeOS devices) + * only exposes the eight I/O ports that are required for the Microchip EC. + * Requesting a larger reservation will fail. + */ + if (!devm_request_region(dev, EC_HOST_CMD_REGION0, + EC_HOST_CMD_MEC_REGION_SIZE, dev_name(dev))) { + dev_err(dev, "couldn't reserve MEC region\n"); return -EBUSY; } @@ -357,6 +362,12 @@ static int cros_ec_lpc_probe(struct platform_device *pdev) cros_ec_lpc_ops.write = cros_ec_lpc_mec_write_bytes; cros_ec_lpc_ops.read(EC_LPC_ADDR_MEMMAP + EC_MEMMAP_ID, 2, buf); if (buf[0] != 'E' || buf[1] != 'C') { + if (!devm_request_region(dev, EC_LPC_ADDR_MEMMAP, EC_MEMMAP_SIZE, + dev_name(dev))) { + dev_err(dev, "couldn't reserve memmap region\n"); + return -EBUSY; + } + /* Re-assign read/write operations for the non MEC variant */ cros_ec_lpc_ops.read = cros_ec_lpc_read_bytes; cros_ec_lpc_ops.write = cros_ec_lpc_write_bytes; @@ -366,17 +377,19 @@ static int cros_ec_lpc_probe(struct platform_device *pdev) dev_err(dev, "EC ID not detected\n"); return -ENODEV; } - } - if (!devm_request_region(dev, EC_HOST_CMD_REGION0, - EC_HOST_CMD_REGION_SIZE, dev_name(dev))) { - dev_err(dev, "couldn't reserve region0\n"); - return -EBUSY; - } - if (!devm_request_region(dev, EC_HOST_CMD_REGION1, - EC_HOST_CMD_REGION_SIZE, dev_name(dev))) { - dev_err(dev, "couldn't reserve region1\n"); - return -EBUSY; + /* Reserve the remaining I/O ports required by the non-MEC protocol. */ + if (!devm_request_region(dev, EC_HOST_CMD_REGION0 + EC_HOST_CMD_MEC_REGION_SIZE, + EC_HOST_CMD_REGION_SIZE - EC_HOST_CMD_MEC_REGION_SIZE, + dev_name(dev))) { + dev_err(dev, "couldn't reserve remainder of region0\n"); + return -EBUSY; + } + if (!devm_request_region(dev, EC_HOST_CMD_REGION1, + EC_HOST_CMD_REGION_SIZE, dev_name(dev))) { + dev_err(dev, "couldn't reserve region1\n"); + return -EBUSY; + } } ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL); diff --git a/include/linux/platform_data/cros_ec_commands.h b/include/linux/platform_data/cros_ec_commands.h index 271bd87bff0a..a85b1176e6c0 100644 --- a/include/linux/platform_data/cros_ec_commands.h +++ b/include/linux/platform_data/cros_ec_commands.h @@ -55,6 +55,10 @@ #define EC_HOST_CMD_REGION0 0x800 #define EC_HOST_CMD_REGION1 0x880 #define EC_HOST_CMD_REGION_SIZE 0x80 +/* + * Other machines report only the region spanned by the Microchip MEC EC. + */ +#define EC_HOST_CMD_MEC_REGION_SIZE 0x08 /* EC command register bit functions */ #define EC_LPC_CMDR_DATA BIT(0) /* Data ready for host to read */ -- 2.34.1
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