iwlwifi: pcie: add workaround for power gating in integrated 22000

Add a workaround that forces power gating to be enabled on integrated
22000 devices.  This improves power saving in certain situations.
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/intel/iwlwifi/iwl-csr.h

@@ -279,6 +279,7 @@
  *         Indicates MAC is entering a power-saving sleep power-down.
  *         Not a good time to access device-internal resources.
  */
+#define CSR_GP_CNTRL_REG_FLAG_INIT_DONE		     (0x00000004)
 #define CSR_GP_CNTRL_REG_FLAG_GOING_TO_SLEEP         (0x00000010)
 #define CSR_GP_CNTRL_REG_FLAG_XTAL_ON		     (0x00000400)
 

drivers/net/wireless/intel/iwlwifi/iwl-prph.h

@@ -449,6 +449,11 @@ enum {
 #define PERSISTENCE_BIT			BIT(12)
 #define PREG_WFPM_ACCESS		BIT(12)
 
+#define HPM_HIPM_GEN_CFG			0xA03458
+#define HPM_HIPM_GEN_CFG_CR_PG_EN		BIT(0)
+#define HPM_HIPM_GEN_CFG_CR_SLP_EN		BIT(1)
+#define HPM_HIPM_GEN_CFG_CR_FORCE_ACTIVE	BIT(10)
+
 #define UREG_DOORBELL_TO_ISR6		0xA05C04
 #define UREG_DOORBELL_TO_ISR6_NMI_BIT	BIT(0)
 #define UREG_DOORBELL_TO_ISR6_SUSPEND	BIT(18)

drivers/net/wireless/intel/iwlwifi/pcie/trans-gen2.c

@@ -57,6 +57,24 @@
 #include "internal.h"
 #include "fw/dbg.h"
 
+static int iwl_pcie_gen2_force_power_gating(struct iwl_trans *trans)
+{
+	iwl_set_bits_prph(trans, HPM_HIPM_GEN_CFG,
+			  HPM_HIPM_GEN_CFG_CR_FORCE_ACTIVE);
+	udelay(20);
+	iwl_set_bits_prph(trans, HPM_HIPM_GEN_CFG,
+			  HPM_HIPM_GEN_CFG_CR_PG_EN |
+			  HPM_HIPM_GEN_CFG_CR_SLP_EN);
+	udelay(20);
+	iwl_clear_bits_prph(trans, HPM_HIPM_GEN_CFG,
+			    HPM_HIPM_GEN_CFG_CR_FORCE_ACTIVE);
+
+	iwl_trans_sw_reset(trans);
+	iwl_clear_bit(trans, CSR_GP_CNTRL, CSR_GP_CNTRL_REG_FLAG_INIT_DONE);
+
+	return 0;
+}
+
 /*
  * Start up NIC's basic functionality after it has been reset
  * (e.g. after platform boot, or shutdown via iwl_pcie_apm_stop())
@@ -92,6 +110,13 @@ int iwl_pcie_gen2_apm_init(struct iwl_trans *trans)
 
 	iwl_pcie_apm_config(trans);
 
+	if (trans->trans_cfg->device_family == IWL_DEVICE_FAMILY_22000 &&
+	    trans->cfg->integrated) {
+		ret = iwl_pcie_gen2_force_power_gating(trans);
+		if (ret)
+			return ret;
+	}
+
 	ret = iwl_finish_nic_init(trans, trans->trans_cfg);
 	if (ret)
 		return ret;