[PATCH v2 07/14] PCI: brcmstb: Add control of rescal reset

From: Jim Quinlan <james.quinlan@broadcom.com>
To: linux-pci@vger.kernel.org, Christoph Hellwig <hch@lst.de>,
	Nicolas Saenz Julienne <nsaenzjulienne@suse.de>,
	bcm-kernel-feedback-list@broadcom.com,
	james.quinlan@broadcom.com
Cc: Jim Quinlan <james.quinlan@broadcom.com>,
	Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
	Rob Herring <robh@kernel.org>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Florian Fainelli <f.fainelli@gmail.com>,
	Philipp Zabel <p.zabel@pengutronix.de>,
	linux-rpi-kernel@lists.infradead.org (moderated list:BROADCOM
	BCM2711/BCM2835 ARM ARCHITECTURE),
	linux-arm-kernel@lists.infradead.org (moderated list:BROADCOM
	BCM2711/BCM2835 ARM ARCHITECTURE),
	linux-kernel@vger.kernel.org (open list)
Subject: [PATCH v2 07/14] PCI: brcmstb: Add control of rescal reset
Date: Tue, 26 May 2020 15:12:46 -0400	[thread overview]
Message-ID: <20200526191303.1492-8-james.quinlan@broadcom.com> (raw)
In-Reply-To: <20200526191303.1492-1-james.quinlan@broadcom.com>

From: Jim Quinlan <jquinlan@broadcom.com>

Some STB chips have a special purpose reset controller named RESCAL (reset
calibration).  The PCIe HW can now control RESCAL to start and stop its
operation.

Signed-off-by: Jim Quinlan <jquinlan@broadcom.com>
---
 drivers/pci/controller/pcie-brcmstb.c | 81 ++++++++++++++++++++++++++-
 1 file changed, 80 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/controller/pcie-brcmstb.c b/drivers/pci/controller/pcie-brcmstb.c
index 0bcae9eba048..fa356bc149c3 100644
--- a/drivers/pci/controller/pcie-brcmstb.c
+++ b/drivers/pci/controller/pcie-brcmstb.c
@@ -23,6 +23,7 @@
 #include <linux/of_platform.h>
 #include <linux/pci.h>
 #include <linux/printk.h>
+#include <linux/reset.h>
 #include <linux/sizes.h>
 #include <linux/slab.h>
 #include <linux/string.h>
@@ -152,7 +153,17 @@
 #define SSC_STATUS_SSC_MASK		0x400
 #define SSC_STATUS_PLL_LOCK_MASK	0x800
 
-#define IDX_ADDR(pcie)	\
+/* Rescal registers */
+#define PCIE_DVT_PMU_PCIE_PHY_CTRL				0xc700
+#define  PCIE_DVT_PMU_PCIE_PHY_CTRL_DAST_NFLDS			0x3
+#define  PCIE_DVT_PMU_PCIE_PHY_CTRL_DAST_DIG_RESET_MASK		0x4
+#define  PCIE_DVT_PMU_PCIE_PHY_CTRL_DAST_DIG_RESET_SHIFT	0x2
+#define  PCIE_DVT_PMU_PCIE_PHY_CTRL_DAST_RESET_MASK		0x2
+#define  PCIE_DVT_PMU_PCIE_PHY_CTRL_DAST_RESET_SHIFT		0x1
+#define  PCIE_DVT_PMU_PCIE_PHY_CTRL_DAST_PWRDN_MASK		0x1
+#define  PCIE_DVT_PMU_PCIE_PHY_CTRL_DAST_PWRDN_SHIFT		0x0
+
+#define IDX_ADDR(pcie) \
 	(pcie->reg_offsets[EXT_CFG_INDEX])
 #define DATA_ADDR(pcie)	\
 	(pcie->reg_offsets[EXT_CFG_DATA])
@@ -249,6 +260,7 @@ struct brcm_pcie {
 	const int		*reg_offsets;
 	const int		*reg_field_info;
 	enum pcie_type		type;
+	struct reset_control	*rescal;
 };
 
 /*
@@ -964,6 +976,47 @@ static void brcm_pcie_enter_l23(struct brcm_pcie *pcie)
 		dev_err(pcie->dev, "failed to enter low-power link state\n");
 }
 
+static int brcm_phy_cntl(struct brcm_pcie *pcie, const int start)
+{
+	static const u32 shifts[PCIE_DVT_PMU_PCIE_PHY_CTRL_DAST_NFLDS] = {
+		PCIE_DVT_PMU_PCIE_PHY_CTRL_DAST_PWRDN_SHIFT,
+		PCIE_DVT_PMU_PCIE_PHY_CTRL_DAST_RESET_SHIFT,
+		PCIE_DVT_PMU_PCIE_PHY_CTRL_DAST_DIG_RESET_SHIFT,};
+	static const u32 masks[PCIE_DVT_PMU_PCIE_PHY_CTRL_DAST_NFLDS] = {
+		PCIE_DVT_PMU_PCIE_PHY_CTRL_DAST_PWRDN_MASK,
+		PCIE_DVT_PMU_PCIE_PHY_CTRL_DAST_RESET_MASK,
+		PCIE_DVT_PMU_PCIE_PHY_CTRL_DAST_DIG_RESET_MASK,};
+	const int beg = start ? 0 : PCIE_DVT_PMU_PCIE_PHY_CTRL_DAST_NFLDS - 1;
+	const int end = start ? PCIE_DVT_PMU_PCIE_PHY_CTRL_DAST_NFLDS : -1;
+	u32 tmp, combined_mask = 0;
+	u32 val = !!start;
+	void __iomem *base = pcie->base;
+	int i;
+
+	for (i = beg; i != end; start ? i++ : i--) {
+		tmp = readl(base + PCIE_DVT_PMU_PCIE_PHY_CTRL);
+		tmp = (tmp & ~masks[i]) | ((val << shifts[i]) & masks[i]);
+		writel(tmp, base + PCIE_DVT_PMU_PCIE_PHY_CTRL);
+		usleep_range(50, 200);
+		combined_mask |= masks[i];
+	}
+
+	tmp = readl(base + PCIE_DVT_PMU_PCIE_PHY_CTRL);
+	val = start ? combined_mask : 0;
+
+	return (tmp & combined_mask) == val ? 0 : -EIO;
+}
+
+static inline int brcm_phy_start(struct brcm_pcie *pcie)
+{
+	return pcie->rescal ? brcm_phy_cntl(pcie, 1) : 0;
+}
+
+static inline int brcm_phy_stop(struct brcm_pcie *pcie)
+{
+	return pcie->rescal ? brcm_phy_cntl(pcie, 0) : 0;
+}
+
 static void brcm_pcie_turn_off(struct brcm_pcie *pcie)
 {
 	void __iomem *base = pcie->base;
@@ -994,6 +1047,9 @@ static int brcm_pcie_suspend(struct device *dev)
 	int ret = 0;
 
 	brcm_pcie_turn_off(pcie);
+	ret = brcm_phy_stop(pcie);
+	if (ret)
+		dev_err(pcie->dev, "failed to stop phy\n");
 	clk_disable_unprepare(pcie->clk);
 
 	return ret;
@@ -1009,6 +1065,12 @@ static int brcm_pcie_resume(struct device *dev)
 	base = pcie->base;
 	clk_prepare_enable(pcie->clk);
 
+	ret = brcm_phy_start(pcie);
+	if (ret) {
+		dev_err(pcie->dev, "failed to start phy\n");
+		return ret;
+	}
+
 	/* Take bridge out of reset so we can access the SERDES reg */
 	brcm_pcie_bridge_sw_init_set(pcie, 0);
 
@@ -1035,6 +1097,9 @@ static void __brcm_pcie_remove(struct brcm_pcie *pcie)
 {
 	brcm_msi_remove(pcie);
 	brcm_pcie_turn_off(pcie);
+	if (brcm_phy_stop(pcie))
+		dev_err(pcie->dev, "failed to stop phy\n");
+	reset_control_assert(pcie->rescal);
 	clk_disable_unprepare(pcie->clk);
 }
 
@@ -1105,6 +1170,20 @@ static int brcm_pcie_probe(struct platform_device *pdev)
 		dev_err(&pdev->dev, "could not enable clock\n");
 		return ret;
 	}
+	pcie->rescal = devm_reset_control_get_optional_shared(&pdev->dev,
+							      "rescal");
+	if (IS_ERR(pcie->rescal))
+		return PTR_ERR(pcie->rescal);
+
+	ret = reset_control_deassert(pcie->rescal);
+	if (ret)
+		dev_err(&pdev->dev, "failed to deassert 'rescal'\n");
+
+	ret = brcm_phy_start(pcie);
+	if (ret) {
+		dev_err(pcie->dev, "failed to start phy\n");
+		return ret;
+	}
 
 	ret = brcm_pcie_setup(pcie);
 	if (ret)
-- 
2.17.1

