linux-kernel - [PATCH v6 06/12] PCI: brcmstb: Add bcm7278 PERST# support

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Message-Id: <20200701212155.37830-7-james.quinlan@broadcom.com>
Date:   Wed,  1 Jul 2020 17:21:36 -0400
From:   Jim Quinlan <james.quinlan@...adcom.com>
To:     linux-pci@...r.kernel.org,
        Nicolas Saenz Julienne <nsaenzjulienne@...e.de>,
        bcm-kernel-feedback-list@...adcom.com, james.quinlan@...adcom.com
Cc:     Jim Quinlan <james.quinlan@...adcom.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Rob Herring <robh@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        linux-rpi-kernel@...ts.infradead.org (moderated list:BROADCOM
        BCM2711/BCM2835 ARM ARCHITECTURE),
        linux-arm-kernel@...ts.infradead.org (moderated list:BROADCOM
        BCM2711/BCM2835 ARM ARCHITECTURE),
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH v6 06/12] PCI: brcmstb: Add bcm7278 PERST# support

From: Jim Quinlan <jquinlan@...adcom.com>

The PERST# bit was moved to a different register in 7278-type STB chips.
In addition, the polarity of the bit was also changed; for other chips
writing a 1 specified assert; for 7278-type chips, writing a 0 specifies
assert.

Of course, PERST# is a PCIe asserted-low signal.

Signed-off-by: Jim Quinlan <jquinlan@...adcom.com>
Acked-by: Florian Fainelli <f.fainelli@...il.com>
---
 drivers/pci/controller/pcie-brcmstb.c | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/controller/pcie-brcmstb.c b/drivers/pci/controller/pcie-brcmstb.c
index 7c148eb65170..e5e7f7d82eda 100644
--- a/drivers/pci/controller/pcie-brcmstb.c
+++ b/drivers/pci/controller/pcie-brcmstb.c
@@ -83,6 +83,7 @@
 
 #define PCIE_MISC_PCIE_CTRL				0x4064
 #define  PCIE_MISC_PCIE_CTRL_PCIE_L23_REQUEST_MASK	0x1
+#define PCIE_MISC_PCIE_CTRL_PCIE_PERSTB_MASK		0x4
 
 #define PCIE_MISC_PCIE_STATUS				0x4068
 #define  PCIE_MISC_PCIE_STATUS_PCIE_PORT_MASK		0x80
@@ -685,9 +686,16 @@ static inline void brcm_pcie_perst_set(struct brcm_pcie *pcie, u32 val)
 {
 	u32 tmp;
 
-	tmp = readl(pcie->base + PCIE_RGR1_SW_INIT_1(pcie));
-	u32p_replace_bits(&tmp, val, PCIE_RGR1_SW_INIT_1_PERST_MASK);
-	writel(tmp, pcie->base + PCIE_RGR1_SW_INIT_1(pcie));
+	if (pcie->type == BCM7278) {
+		/* Perst bit has moved and assert value is 0 */
+		tmp = readl(pcie->base + PCIE_MISC_PCIE_CTRL);
+		u32p_replace_bits(&tmp, !val, PCIE_MISC_PCIE_CTRL_PCIE_PERSTB_MASK);
+		writel(tmp, pcie->base +  PCIE_MISC_PCIE_CTRL);
+	} else {
+		tmp = readl(pcie->base + PCIE_RGR1_SW_INIT_1(pcie));
+		u32p_replace_bits(&tmp, val, PCIE_RGR1_SW_INIT_1_PERST_MASK);
+		writel(tmp, pcie->base + PCIE_RGR1_SW_INIT_1(pcie));
+	}
 }
 
 static inline int brcm_pcie_get_rc_bar2_size_and_offset(struct brcm_pcie *pcie,
@@ -772,7 +780,10 @@ static int brcm_pcie_setup(struct brcm_pcie *pcie)
 
 	/* Reset the bridge */
 	brcm_pcie_bridge_sw_init_set(pcie, 1);
-	brcm_pcie_perst_set(pcie, 1);
+
+	/* BCM7278 fails when PERST# is set here */
+	if (pcie->type != BCM7278)
+		brcm_pcie_perst_set(pcie, 1);
 
 	usleep_range(100, 200);
 
-- 
2.17.1