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Message-ID: <3839884.FkOqQZPJsr@vostro.rjw.lan>
Date: Mon, 05 Oct 2015 15:47:26 +0200
From: "Rafael J. Wysocki" <rjw@...ysocki.net>
To: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc: linux-acpi@...r.kernel.org, linux-i2c@...r.kernel.org,
linux-gpio@...r.kernel.org, Lee Jones <lee.jones@...aro.org>,
Wolfram Sang <wsa@...-dreams.de>,
Linus Walleij <linus.walleij@...aro.org>,
Mika Westerberg <mika.westerberg@...el.com>,
"Puustinen, Ismo" <ismo.puustinen@...el.com>,
"Pandruvada, Srinivas" <srinivas.pandruvada@...el.com>,
linux-kernel@...r.kernel.org,
Mika Westerberg <mika.westerberg@...ux.intel.com>
Subject: Re: [PATCH v2 1/8] i2c / ACPI: Rework I2C device scanning
On Thursday, October 01, 2015 02:20:23 PM Andy Shevchenko wrote:
> From: Mika Westerberg <mika.westerberg@...ux.intel.com>
>
> The way we currently scan I2C devices behind an I2C host controller does not
> work in cases where the I2C device in question is not declared directly below
> the host controller ACPI node.
>
> This is perfectly legal according the ACPI 6.0 specification and some existing
> systems are doing this.
>
> To be able to enumerate all devices which are connected to a certain I2C host
> controller we need to rework the current I2C scanning routine a bit. Instead of
> scanning directly below the host controller we scan the whole ACPI namespace
> for present devices with valid I2cSerialBus() connection pointing to the host
> controller in question.
>
> Signed-off-by: Mika Westerberg <mika.westerberg@...ux.intel.com>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> ---
> drivers/i2c/i2c-core.c | 82 ++++++++++++++++++++++++++++++++++++--------------
> 1 file changed, 59 insertions(+), 23 deletions(-)
>
> diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
> index a732107..24e516e 100644
> --- a/drivers/i2c/i2c-core.c
> +++ b/drivers/i2c/i2c-core.c
> @@ -99,27 +99,40 @@ struct gsb_buffer {
> };
> } __packed;
>
> -static int acpi_i2c_add_resource(struct acpi_resource *ares, void *data)
> +struct acpi_i2c_lookup {
> + struct i2c_board_info *info;
> + acpi_handle adapter_handle;
> + acpi_handle device_handle;
> +};
> +
> +static int acpi_i2c_find_address(struct acpi_resource *ares, void *data)
> {
> - struct i2c_board_info *info = data;
> + struct acpi_i2c_lookup *lookup = data;
> + struct i2c_board_info *info = lookup->info;
> + struct acpi_resource_i2c_serialbus *sb;
> + acpi_handle adapter_handle;
> + acpi_status status;
>
> - if (ares->type == ACPI_RESOURCE_TYPE_SERIAL_BUS) {
> - struct acpi_resource_i2c_serialbus *sb;
> + if (info->addr || ares->type != ACPI_RESOURCE_TYPE_SERIAL_BUS)
> + return 1;
>
> - sb = &ares->data.i2c_serial_bus;
> - if (!info->addr && sb->type == ACPI_RESOURCE_SERIAL_TYPE_I2C) {
> - info->addr = sb->slave_address;
> - if (sb->access_mode == ACPI_I2C_10BIT_MODE)
> - info->flags |= I2C_CLIENT_TEN;
> - }
> - } else if (!info->irq) {
> - struct resource r;
> + sb = &ares->data.i2c_serial_bus;
> + if (sb->type != ACPI_RESOURCE_SERIAL_TYPE_I2C)
> + return 1;
>
> - if (acpi_dev_resource_interrupt(ares, 0, &r))
> - info->irq = r.start;
> + /*
> + * Extract the ResourceSource and make sure that the handle matches
> + * with the I2C adapter handle.
> + */
> + status = acpi_get_handle(lookup->device_handle,
> + sb->resource_source.string_ptr,
> + &adapter_handle);
> + if (ACPI_SUCCESS(status) && adapter_handle == lookup->adapter_handle) {
> + info->addr = sb->slave_address;
> + if (sb->access_mode == ACPI_I2C_10BIT_MODE)
> + info->flags |= I2C_CLIENT_TEN;
> }
>
> - /* Tell the ACPI core to skip this resource */
> return 1;
> }
>
> @@ -128,6 +141,8 @@ static acpi_status acpi_i2c_add_device(acpi_handle handle, u32 level,
> {
> struct i2c_adapter *adapter = data;
> struct list_head resource_list;
> + struct acpi_i2c_lookup lookup;
> + struct resource_entry *entry;
> struct i2c_board_info info;
> struct acpi_device *adev;
> int ret;
> @@ -140,14 +155,37 @@ static acpi_status acpi_i2c_add_device(acpi_handle handle, u32 level,
> memset(&info, 0, sizeof(info));
> info.fwnode = acpi_fwnode_handle(adev);
>
> + memset(&lookup, 0, sizeof(lookup));
> + lookup.adapter_handle = ACPI_HANDLE(adapter->dev.parent);
> + lookup.device_handle = handle;
> + lookup.info = &info;
> +
> + /*
> + * Look up for I2cSerialBus resource with ResourceSource that
> + * matches with this adapter.
> + */
> INIT_LIST_HEAD(&resource_list);
> ret = acpi_dev_get_resources(adev, &resource_list,
> - acpi_i2c_add_resource, &info);
> + acpi_i2c_find_address, &lookup);
> acpi_dev_free_resource_list(&resource_list);
>
> if (ret < 0 || !info.addr)
> return AE_OK;
>
> + /* Then fill IRQ number if any */
> + ret = acpi_dev_get_resources(adev, &resource_list, NULL, NULL);
> + if (ret < 0)
> + return AE_OK;
> +
> + resource_list_for_each_entry(entry, &resource_list) {
> + if (resource_type(entry->res) == IORESOURCE_IRQ) {
> + info.irq = entry->res->start;
> + break;
> + }
> + }
> +
> + acpi_dev_free_resource_list(&resource_list);
> +
> adev->power.flags.ignore_parent = true;
> strlcpy(info.type, dev_name(&adev->dev), sizeof(info.type));
> if (!i2c_new_device(adapter, &info)) {
> @@ -160,6 +198,8 @@ static acpi_status acpi_i2c_add_device(acpi_handle handle, u32 level,
> return AE_OK;
> }
>
> +#define ACPI_I2C_MAX_SCAN_DEPTH 32
> +
> /**
> * acpi_i2c_register_devices - enumerate I2C slave devices behind adapter
> * @adap: pointer to adapter
> @@ -170,17 +210,13 @@ static acpi_status acpi_i2c_add_device(acpi_handle handle, u32 level,
> */
> static void acpi_i2c_register_devices(struct i2c_adapter *adap)
> {
> - acpi_handle handle;
> acpi_status status;
>
> - if (!adap->dev.parent)
> - return;
> -
> - handle = ACPI_HANDLE(adap->dev.parent);
> - if (!handle)
> + if (!adap->dev.parent || !has_acpi_companion(adap->dev.parent))
> return;
>
> - status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, 1,
> + status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
> + ACPI_I2C_MAX_SCAN_DEPTH,
> acpi_i2c_add_device, NULL,
> adap, NULL);
> if (ACPI_FAILURE(status))
>
--
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