[PATCH v4 07/12] PCI: brcmstb: Add control of rescal reset

Jim Quinlan
2020-06-05T21:27:38Z

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>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
---
drivers/pci/controller/pcie-brcmstb.c | 84 ++++++++++++++++++++++++++-
1 file changed, 82 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/controller/pcie-brcmstb.c b/drivers/pci/controller/pcie-brcmstb.c
index 532ea9c9cf89..ca825d7ca4fc 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;
@@ -991,11 +1044,15 @@ static void brcm_pcie_turn_off(struct brcm_pcie *pcie)
static int brcm_pcie_suspend(struct device *dev)
{
struct brcm_pcie *pcie = dev_get_drvdata(dev);
+ int ret;

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 0;
+ return ret;
}

static int brcm_pcie_resume(struct device *dev)
@@ -1008,6 +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);

@@ -1034,6 +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);
}

@@ -1104,6 +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