Re: [PATCH v5 07/12] PCI: brcmstb: Add control of rescal reset
From: Jim Quinlan
Date: Wed Jun 17 2020 - 13:33:03 EST
On Tue, Jun 16, 2020 at 6:05 PM Bjorn Helgaas <helgaas@xxxxxxxxxx> wrote:
>
> On Tue, Jun 16, 2020 at 04:55:14PM -0400, Jim Quinlan wrote:
> > From: Jim Quinlan <jquinlan@xxxxxxxxxxxx>
> >
> > 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.
>
> The HW *can* now control RESCAL, but what does this patch do?
>
> I guess maybe this patch uses RESCAL to turn on the PHY in probe and
> resume and turn it off in suspend and remove?
Yes, I will redo this text with a better description.
Thanks,
Jim
PS Will attend to your other responses as well in the V6.
>
> > Signed-off-by: Jim Quinlan <jquinlan@xxxxxxxxxxxx>
> > Acked-by: Florian Fainelli <f.fainelli@xxxxxxxxx>
> > ---
> > 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 d0e256d8578a..9189406fd35c 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>
> > @@ -158,6 +159,16 @@
> > #define DATA_ADDR(pcie) (pcie->reg_offsets[EXT_CFG_DATA])
> > #define PCIE_RGR1_SW_INIT_1(pcie) (pcie->reg_offsets[RGR1_SW_INIT_1])
> >
> > +/* 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
> > +
> > enum {
> > RGR1_SW_INIT_1,
> > EXT_CFG_INDEX,
> > @@ -248,6 +259,7 @@ struct brcm_pcie {
> > const int *reg_offsets;
> > const int *reg_field_info;
> > enum pcie_type type;
> > + struct reset_control *rescal;
> > };
> >
> > /*
> > @@ -963,6 +975,47 @@ 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;
> > @@ -990,11 +1043,15 @@ 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)
> > @@ -1007,6 +1064,12 @@ 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);
> >
> > @@ -1032,6 +1095,9 @@ 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);
> > }
> >
> > @@ -1117,6 +1183,19 @@ 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
> >