[2/2] wifi: brcmfmac: support brcm,ccode-map-trivial DT property

From: Alvin Šipraga <alsi@bang-olufsen.dk>

Commit a21bf90e927f ("brcmfmac: use ISO3166 country code and 0 rev as
fallback on some devices") introduced a fallback mechanism whereby a
trivial mapping from ISO3166 country codes to firmware country code and
revision is used on some devices. This fallback operates on the device
level, so it is enabled only for certain supported chipsets.

In general though, the firmware country codes are determined by the CLM
blob, which is board-specific and may vary despite the underlying
chipset being the same.

The aforementioned commit is actually a refinement of a previous commit
that was reverted in commit 151a7c12c4fc ("Revert "brcmfmac: use ISO3166
country code and 0 rev as fallback"") due to regressions with a BCM4359
device. The refinement restricted the fallback mechanism to specific
chipsets such as the BCM4345.

We use a chipset - CYW88359 - that the driver identifies as a BCM4359
too. But in our case, the CLM blob uses ISO3166 country codes
internally, and all with revision 0. So the trivial mapping is exactly
what is needed in order for the driver to sync the kernel regulatory
domain to the firmware. This is just a matter of how the CLM blob was
prepared by the hardware vendor. The same could hold for other boards
too.

Although the brcm,ccode-map device tree property is useful for cases
where the mapping is more complex, the trivial case invites a much
simpler specification. This patch adds support for parsing the
brcm,ccode-map-trivial device tree property. Subordinate to the more
specific brcm,ccode-map property, this new proprety simply informs the
driver that the fallback method should be used in every case.

In the absence of the new property in the device tree, expect no
functional change.

Signed-off-by: Alvin Šipraga <alsi@bang-olufsen.dk>
---
 drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c | 3 +++
 drivers/net/wireless/broadcom/brcm80211/brcmfmac/common.h   | 2 ++
 drivers/net/wireless/broadcom/brcm80211/brcmfmac/of.c       | 6 ++++++
 3 files changed, 11 insertions(+)

On 11.07.22 14:30, Alvin Šipraga wrote:
> From: Alvin Šipraga <alsi@bang-olufsen.dk>
> 
> Commit a21bf90e927f ("brcmfmac: use ISO3166 country code and 0 rev as
> fallback on some devices") introduced a fallback mechanism whereby a
> trivial mapping from ISO3166 country codes to firmware country code and
> revision is used on some devices. This fallback operates on the device
> level, so it is enabled only for certain supported chipsets.
> 
> In general though, the firmware country codes are determined by the CLM
> blob, which is board-specific and may vary despite the underlying
> chipset being the same.
> 
> The aforementioned commit is actually a refinement of a previous commit
> that was reverted in commit 151a7c12c4fc ("Revert "brcmfmac: use ISO3166
> country code and 0 rev as fallback"") due to regressions with a BCM4359
> device. The refinement restricted the fallback mechanism to specific
> chipsets such as the BCM4345.
> 
> We use a chipset - CYW88359 - that the driver identifies as a BCM4359
> too. But in our case, the CLM blob uses ISO3166 country codes
> internally, and all with revision 0. So the trivial mapping is exactly
> what is needed in order for the driver to sync the kernel regulatory
> domain to the firmware. This is just a matter of how the CLM blob was
> prepared by the hardware vendor. The same could hold for other boards
> too.
> 
> Although the brcm,ccode-map device tree property is useful for cases
> where the mapping is more complex, the trivial case invites a much
> simpler specification. This patch adds support for parsing the
> brcm,ccode-map-trivial device tree property. Subordinate to the more
> specific brcm,ccode-map property, this new proprety simply informs the
> driver that the fallback method should be used in every case.
> 
> In the absence of the new property in the device tree, expect no
> functional change.
> 
> Signed-off-by: Alvin Šipraga <alsi@bang-olufsen.dk>

Reviewed-by: Ahmad Fatoum <a.fatoum@pengutronix.de>

> ---
>  drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c | 3 +++
>  drivers/net/wireless/broadcom/brcm80211/brcmfmac/common.h   | 2 ++
>  drivers/net/wireless/broadcom/brcm80211/brcmfmac/of.c       | 6 ++++++
>  3 files changed, 11 insertions(+)
> 
> diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c
> index 3ae6779fe153..db45da33adfd 100644
> --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c
> +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c
> @@ -7481,6 +7481,9 @@ int brcmf_cfg80211_wait_vif_event(struct brcmf_cfg80211_info *cfg,
>  
>  static bool brmcf_use_iso3166_ccode_fallback(struct brcmf_pub *drvr)
>  {
> +	if (drvr->settings->trivial_ccode_map)
> +		return true;
> +
>  	switch (drvr->bus_if->chip) {
>  	case BRCM_CC_4345_CHIP_ID:
>  	case BRCM_CC_43602_CHIP_ID:
> diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/common.h b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/common.h
> index 15accc88d5c0..fe717cce5d55 100644
> --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/common.h
> +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/common.h
> @@ -38,6 +38,7 @@ extern struct brcmf_mp_global_t brcmf_mp_global;
>   * @fcmode: FWS flow control.
>   * @roamoff: Firmware roaming off?
>   * @ignore_probe_fail: Ignore probe failure.
> + * @trivial_ccode_map: Assume firmware uses ISO3166 country codes with rev 0
>   * @country_codes: If available, pointer to struct for translating country codes
>   * @bus: Bus specific platform data. Only SDIO at the mmoment.
>   */
> @@ -48,6 +49,7 @@ struct brcmf_mp_device {
>  	bool		roamoff;
>  	bool		iapp;
>  	bool		ignore_probe_fail;
> +	bool		trivial_ccode_map;
>  	struct brcmfmac_pd_cc *country_codes;
>  	const char	*board_type;
>  	unsigned char	mac[ETH_ALEN];
> diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/of.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/of.c
> index 083ac58f466d..1add942462f8 100644
> --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/of.c
> +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/of.c
> @@ -24,6 +24,12 @@ static int brcmf_of_get_country_codes(struct device *dev,
>  
>  	count = of_property_count_strings(np, "brcm,ccode-map");
>  	if (count < 0) {
> +		/* If no explicit country code map is specified, check whether
> +		 * the trivial map should be used.
> +		 */
> +		settings->trivial_ccode_map =
> +			of_property_read_bool(np, "brcm,ccode-map-trivial");
> +
>  		/* The property is optional, so return success if it doesn't
>  		 * exist. Otherwise propagate the error code.
>  		 */