ath11k: pci: fix hot reset stability issues

For QCA6390, host needs to reset some registers before MHI power up to fix PCI
link unstable issue if hot reset happened. Also clear all pending interrupts
during power up.

Tested-on: QCA6390 hw2.0 PCI WLAN.HST.1.0.1-01740-QCAHSTSWPLZ_V2_TO_X86-1
Signed-off-by: Carl Huang <cjhuang@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/1607609124-17250-4-git-send-email-kvalo@codeaurora.org

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

@@ -239,15 +239,57 @@ static void ath11k_pci_clear_dbg_registers(struct ath11k_base *ab)
 	ath11k_dbg(ab, ATH11K_DBG_PCI, "soc reset cause:%d\n", val);
 }
 
+static void ath11k_pci_enable_ltssm(struct ath11k_base *ab)
+{
+	u32 val;
+	int i;
+
+	val = ath11k_pci_read32(ab, PCIE_PCIE_PARF_LTSSM);
+
+	/* PCIE link seems very unstable after the Hot Reset*/
+	for (i = 0; val != PARM_LTSSM_VALUE && i < 5; i++) {
+		if (val == 0xffffffff)
+			mdelay(5);
+
+		ath11k_pci_write32(ab, PCIE_PCIE_PARF_LTSSM, PARM_LTSSM_VALUE);
+		val = ath11k_pci_read32(ab, PCIE_PCIE_PARF_LTSSM);
+	}
+
+	ath11k_dbg(ab, ATH11K_DBG_PCI, "pci ltssm 0x%x\n", val);
+
+	val = ath11k_pci_read32(ab, GCC_GCC_PCIE_HOT_RST);
+	val |= GCC_GCC_PCIE_HOT_RST_VAL | 0x10;
+	ath11k_pci_write32(ab, GCC_GCC_PCIE_HOT_RST, val);
+	val = ath11k_pci_read32(ab, GCC_GCC_PCIE_HOT_RST);
+
+	ath11k_dbg(ab, ATH11K_DBG_PCI, "pci pcie_hot_rst 0x%x\n", val);
+
+	mdelay(5);
+}
+
+static void ath11k_pci_clear_all_intrs(struct ath11k_base *ab)
+{
+	/* This is a WAR for PCIE Hotreset.
+	 * When target receive Hotreset, but will set the interrupt.
+	 * So when download SBL again, SBL will open Interrupt and
+	 * receive it, and crash immediately.
+	 */
+	ath11k_pci_write32(ab, PCIE_PCIE_INT_ALL_CLEAR, PCIE_INT_CLEAR_ALL);
+}
+
 static void ath11k_pci_force_wake(struct ath11k_base *ab)
 {
 	ath11k_pci_write32(ab, PCIE_SOC_WAKE_PCIE_LOCAL_REG, 1);
 	mdelay(5);
 }
 
-static void ath11k_pci_sw_reset(struct ath11k_base *ab)
+static void ath11k_pci_sw_reset(struct ath11k_base *ab, bool power_on)
 {
-	ath11k_pci_soc_global_reset(ab);
+	if (power_on) {
+		ath11k_pci_enable_ltssm(ab);
+		ath11k_pci_clear_all_intrs(ab);
+	}
+
 	ath11k_mhi_clear_vector(ab);
 	ath11k_pci_soc_global_reset(ab);
 	ath11k_mhi_set_mhictrl_reset(ab);
@@ -770,7 +812,7 @@ static int ath11k_pci_power_up(struct ath11k_base *ab)
 
 	ab_pci->register_window = 0;
 	clear_bit(ATH11K_PCI_FLAG_INIT_DONE, &ab_pci->flags);
-	ath11k_pci_sw_reset(ab_pci->ab);
+	ath11k_pci_sw_reset(ab_pci->ab, true);
 
 	ret = ath11k_mhi_start(ab_pci);
 	if (ret) {
@@ -785,10 +827,10 @@ static void ath11k_pci_power_down(struct ath11k_base *ab)
 {
 	struct ath11k_pci *ab_pci = ath11k_pci_priv(ab);
 
+	ath11k_pci_force_wake(ab_pci->ab);
 	ath11k_mhi_stop(ab_pci);
 	clear_bit(ATH11K_PCI_FLAG_INIT_DONE, &ab_pci->flags);
-	ath11k_pci_force_wake(ab_pci->ab);
-	ath11k_pci_sw_reset(ab_pci->ab);
+	ath11k_pci_sw_reset(ab_pci->ab, false);
 }
 
 static void ath11k_pci_kill_tasklets(struct ath11k_base *ab)

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

@@ -24,6 +24,16 @@
 /* register used for handshake mechanism to validate UMAC is awake */
 #define PCIE_SOC_WAKE_PCIE_LOCAL_REG		0x3004
 
+#define PCIE_PCIE_PARF_LTSSM			0x1e081b0
+#define PARM_LTSSM_VALUE			0x111
+
+#define GCC_GCC_PCIE_HOT_RST			0x1e402bc
+#define GCC_GCC_PCIE_HOT_RST_VAL		0x10
+
+#define PCIE_PCIE_INT_ALL_CLEAR			0x1e08228
+#define PCIE_SMLH_REQ_RST_LINK_DOWN		0x2
+#define PCIE_INT_CLEAR_ALL			0xffffffff
+
 struct ath11k_msi_user {
 	char *name;
 	int num_vectors;