Messages in this thread | | | Date | Sun, 10 Mar 2024 07:27:29 +0100 | Subject | Re: [PATCH v4 1/2] platform/x86: wmi: Support reading/writing 16 bit EC values | From | Armin Wolf <> |
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Am 10.03.24 um 03:39 schrieb Kuppuswamy Sathyanarayanan:
> On Sat, Mar 9, 2024 at 11:17 AM Armin Wolf <W_Armin@gmx.de> wrote: >> Am 09.03.24 um 18:07 schrieb Kuppuswamy Sathyanarayanan: >> >>> On 3/8/24 1:05 PM, Armin Wolf wrote: >>>> The ACPI EC address space handler currently only supports >>>> reading/writing 8 bit values. Some firmware implementations however >>>> want to access for example 16 bit values, which is prefectly legal > /s/prefectly/perfectly > >>>> according to the ACPI spec. >>>> >>>> Add support for reading/writing such values. >>>> >>>> Tested on a Dell Inspiron 3505 and a Asus Prime B650-Plus. >>>> >>>> Signed-off-by: Armin Wolf <W_Armin@gmx.de> >>>> --- >>>> Changes since v3: >>>> - change type of variable i to size_t >>>> >>>> Changes since v2: >>>> - fix address overflow check >>>> >>>> Changes since v1: >>>> - use BITS_PER_BYTE >>>> - validate that number of bytes to read/write does not overflow the >>>> address >>>> --- >>>> drivers/platform/x86/wmi.c | 49 ++++++++++++++++++++++++++++++-------- >>>> 1 file changed, 39 insertions(+), 10 deletions(-) >>>> >>>> diff --git a/drivers/platform/x86/wmi.c b/drivers/platform/x86/wmi.c >>>> index 1920e115da89..d9bf6d452b3a 100644 >>>> --- a/drivers/platform/x86/wmi.c >>>> +++ b/drivers/platform/x86/wmi.c >>>> @@ -1153,6 +1153,34 @@ static int parse_wdg(struct device *wmi_bus_dev, struct platform_device *pdev) >>>> return 0; >>>> } >>>> >>>> +static int ec_read_multiple(u8 address, u8 *buffer, size_t bytes) >>>> +{ >>>> + size_t i; >>>> + int ret; >>>> + >>>> + for (i = 0; i < bytes; i++) { >>>> + ret = ec_read(address + i, &buffer[i]); >>>> + if (ret < 0) >>>> + return ret; >>>> + } >>>> + >>>> + return 0; >>>> +} >>> Why not use ec_transaction? >> Hi, >> >> because ec_transaction() is meant to send raw commands to the EC. And AFAIK read/write transactions can only transfer a >> single byte at once, so using ec_transaction() would yield no benefit here. > From the implementation, I don't see any length restriction. If it is > a functional restriction, then fine. > > int ec_transaction(u8 command, > const u8 *wdata, unsigned wdata_len, > u8 *rdata, unsigned rdata_len) > { > struct transaction t = {.command = command, > .wdata = wdata, .rdata = rdata, > .wlen = wdata_len, .rlen = rdata_len}; > > if (!first_ec) > return -ENODEV; > > return acpi_ec_transaction(first_ec, &t); > } > EXPORT_SYMBOL(ec_transaction);
Since we are using the ACPI_EC_COMMAND_READ/_WRITE, we can only read/write a single byte, as specified in ACPI (12.3.1 and 12.3.2).
Thanks, Armin Wolf
>>>> + >>>> +static int ec_write_multiple(u8 address, u8 *buffer, size_t bytes) >>>> +{ >>>> + size_t i; >>>> + int ret; >>>> + >>>> + for (i = 0; i < bytes; i++) { >>>> + ret = ec_write(address + i, buffer[i]); >>>> + if (ret < 0) >>>> + return ret; >>>> + } >>>> + >>>> + return 0; >>>> +} >>> Same as above. >>>> + >>>> /* >>>> * WMI can have EmbeddedControl access regions. In which case, we just want to >>>> * hand these off to the EC driver. >>>> @@ -1162,27 +1190,28 @@ acpi_wmi_ec_space_handler(u32 function, acpi_physical_address address, >>>> u32 bits, u64 *value, >>>> void *handler_context, void *region_context) >>>> { >>>> - int result = 0; >>>> - u8 temp = 0; >>>> + int bytes = bits / BITS_PER_BYTE; >>>> + int ret; >>>> + >>>> + if (!value) >>>> + return AE_NULL_ENTRY; >>>> >>>> - if ((address > 0xFF) || !value) >>>> + if (!bytes || bytes > sizeof(*value)) >>>> return AE_BAD_PARAMETER; >>>> >>>> - if (function != ACPI_READ && function != ACPI_WRITE) >>>> + if (address > U8_MAX || address + bytes - 1 > U8_MAX) >>>> return AE_BAD_PARAMETER; >>>> >>>> - if (bits != 8) >>> Since you want to support only 16 bit reads/writes, can you check for >16 >> The 16 bit reads/writes where meant as an example, ACPI code can request much larger values. >> The WMI EC handler should be able to handle those, just like the regular ACPI EC handler. >> > Got it. > >> Thanks, >> Armin Wolf >> >>>> + if (function != ACPI_READ && function != ACPI_WRITE) >>>> return AE_BAD_PARAMETER; >>>> >>>> if (function == ACPI_READ) { >>>> - result = ec_read(address, &temp); >>>> - *value = temp; >>>> + ret = ec_read_multiple(address, (u8 *)value, bytes); >>>> } else { >>>> - temp = 0xff & *value; >>>> - result = ec_write(address, temp); >>>> + ret = ec_write_multiple(address, (u8 *)value, bytes); >>>> } >>>> >>>> - switch (result) { >>>> + switch (ret) { >>>> case -EINVAL: >>>> return AE_BAD_PARAMETER; >>>> case -ENODEV: >>>> -- >>>> 2.39.2 >>>> >>>>
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