Messages in this thread | | | From | Tzung-Bi Shih <> | Date | Tue, 25 Jan 2022 11:42:29 +0800 | Subject | Re: [PATCH 2/2] platform/chrome: reserve only the I/O ports required for the MEC EC |
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On Tue, Jan 25, 2022 at 9:35 AM Dustin L. Howett <dustin@howett.net> wrote: > > 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@howett.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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