wifi: ath11k: Use RMW accessors for changing LNKCTL

Don't assume that only the driver would be accessing LNKCTL. ASPM policy
changes can trigger write to LNKCTL outside of driver's control.

Use RMW capability accessors which do proper locking to avoid losing
concurrent updates to the register value. On restore, clear the ASPMC field
properly.

Suggested-by: Lukas Wunner <lukas@wunner.de>
Fixes: e9603f4 ("ath11k: pci: disable ASPM L0sLs before downloading firmware")
Link: https://lore.kernel.org/r/20230717120503.15276-9-ilpo.jarvinen@linux.intel.com
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Acked-by: Kalle Valo <kvalo@kernel.org>

Author: ij-intel

drivers/net/wireless/ath/ath11k/pci.c

@@ -581,17 +581,19 @@ static void ath11k_pci_aspm_disable(struct ath11k_pci *ab_pci)
 		   u16_get_bits(ab_pci->link_ctl, PCI_EXP_LNKCTL_ASPM_L1));
 
 	/* disable L0s and L1 */
-	pcie_capability_write_word(ab_pci->pdev, PCI_EXP_LNKCTL,
-				   ab_pci->link_ctl & ~PCI_EXP_LNKCTL_ASPMC);
+	pcie_capability_clear_word(ab_pci->pdev, PCI_EXP_LNKCTL,
+				   PCI_EXP_LNKCTL_ASPMC);
 
 	set_bit(ATH11K_PCI_ASPM_RESTORE, &ab_pci->flags);
 }
 
 static void ath11k_pci_aspm_restore(struct ath11k_pci *ab_pci)
 {
 	if (test_and_clear_bit(ATH11K_PCI_ASPM_RESTORE, &ab_pci->flags))
-		pcie_capability_write_word(ab_pci->pdev, PCI_EXP_LNKCTL,
-					   ab_pci->link_ctl);
+		pcie_capability_clear_and_set_word(ab_pci->pdev, PCI_EXP_LNKCTL,
+						   PCI_EXP_LNKCTL_ASPMC,
+						   ab_pci->link_ctl &
+						   PCI_EXP_LNKCTL_ASPMC);
 }
 
 static int ath11k_pci_power_up(struct ath11k_base *ab)