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Message-Id: <20220106160332.2143-7-jim2101024@gmail.com>
Date: Thu, 6 Jan 2022 11:03:29 -0500
From: Jim Quinlan <jim2101024@...il.com>
To: linux-pci@...r.kernel.org, Bjorn Helgaas <bhelgaas@...gle.com>,
Nicolas Saenz Julienne <nsaenz@...nel.org>,
Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
Rob Herring <robh@...nel.org>, Mark Brown <broonie@...nel.org>,
bcm-kernel-feedback-list@...adcom.com, jim2101024@...il.com,
james.quinlan@...adcom.com
Cc: Florian Fainelli <f.fainelli@...il.com>,
Krzysztof Wilczyński <kw@...ux.com>,
Philipp Zabel <p.zabel@...gutronix.de>,
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 v11 6/7] PCI: brcmstb: Add control of subdevice voltage regulators
This Broadcom STB PCIe RC driver has one port and connects directly to one
device, be it a switch or an endpoint. We want to be able to leverage
the recently added mechansim that allocates and turns on/off subdevice
regulators.
All that needs to be done is to put the regulator DT nodes in the bridge
below host and to set the pci_ops methods add_bus and remove_bus.
Note that the pci_subdev_regulators_add_bus() method is wrapped for two
reasons:
1. To acheive linkup after the voltage regulators are turned on.
2. If, in the case of an unsuccessful linkup, to redirect
any PCIe accesses to subdevices, e.g. the scan for
DEV/ID. This redirection is needed because the Broadcom
PCIe HW wil issue a CPU abort if such an access is made when
there is no linkup.
Signed-off-by: Jim Quinlan <jim2101024@...il.com>
---
drivers/pci/controller/pcie-brcmstb.c | 82 +++++++++++++++++++++++++--
1 file changed, 77 insertions(+), 5 deletions(-)
diff --git a/drivers/pci/controller/pcie-brcmstb.c b/drivers/pci/controller/pcie-brcmstb.c
index 7d46eccf17ff..3c1b2fefe7e1 100644
--- a/drivers/pci/controller/pcie-brcmstb.c
+++ b/drivers/pci/controller/pcie-brcmstb.c
@@ -192,6 +192,8 @@ static inline void brcm_pcie_bridge_sw_init_set_generic(struct brcm_pcie *pcie,
static inline void brcm_pcie_perst_set_4908(struct brcm_pcie *pcie, u32 val);
static inline void brcm_pcie_perst_set_7278(struct brcm_pcie *pcie, u32 val);
static inline void brcm_pcie_perst_set_generic(struct brcm_pcie *pcie, u32 val);
+static int brcm_pcie_linkup(struct brcm_pcie *pcie);
+static int brcm_pcie_add_bus(struct pci_bus *bus);
enum {
RGR1_SW_INIT_1,
@@ -304,6 +306,8 @@ struct brcm_pcie {
u32 hw_rev;
void (*perst_set)(struct brcm_pcie *pcie, u32 val);
void (*bridge_sw_init_set)(struct brcm_pcie *pcie, u32 val);
+ bool refusal_mode;
+ struct subdev_regulators *sr;
};
/*
@@ -467,6 +471,34 @@ static int pci_subdev_regulators_add_bus(struct pci_bus *bus)
return 0;
}
+static int brcm_pcie_add_bus(struct pci_bus *bus)
+{
+ struct device *dev = &bus->dev;
+ struct brcm_pcie *pcie = (struct brcm_pcie *) bus->sysdata;
+ int ret;
+
+ if (!dev->of_node || !bus->parent || !pci_is_root_bus(bus->parent))
+ return 0;
+
+ ret = pci_subdev_regulators_add_bus(bus);
+ if (ret)
+ return ret;
+
+ /* Grab the regulators for suspend/resume */
+ pcie->sr = bus->dev.driver_data;
+
+ /*
+ * If we have failed linkup there is no point to return an error as
+ * currently it will cause a WARNING() from pci_alloc_child_bus().
+ * We return 0 and turn on the "refusal_mode" so that any further
+ * accesses to the pci_dev just get 0xffffffff
+ */
+ if (brcm_pcie_linkup(pcie) != 0)
+ pcie->refusal_mode = true;
+
+ return 0;
+}
+
static void pci_subdev_regulators_remove_bus(struct pci_bus *bus)
{
struct device *dev = &bus->dev;
@@ -785,6 +817,18 @@ static void __iomem *brcm_pcie_map_conf(struct pci_bus *bus, unsigned int devfn,
/* Accesses to the RC go right to the RC registers if slot==0 */
if (pci_is_root_bus(bus))
return PCI_SLOT(devfn) ? NULL : base + where;
+ if (pcie->refusal_mode) {
+ /*
+ * At this point we do not have link. There will be a CPU
+ * abort -- a quirk with this controller --if Linux tries
+ * to read any config-space registers besides those
+ * targeting the host bridge. To prevent this we hijack
+ * the address to point to a safe access that will return
+ * 0xffffffff.
+ */
+ writel(0xffffffff, base + PCIE_MISC_RC_BAR2_CONFIG_HI);
+ return base + PCIE_MISC_RC_BAR2_CONFIG_HI + (where & 0x3);
+ }
/* For devices, write to the config space index register */
idx = PCIE_ECAM_OFFSET(bus->number, devfn, 0);
@@ -796,7 +840,7 @@ static struct pci_ops brcm_pcie_ops = {
.map_bus = brcm_pcie_map_conf,
.read = pci_generic_config_read,
.write = pci_generic_config_write,
- .add_bus = pci_subdev_regulators_add_bus,
+ .add_bus = brcm_pcie_add_bus,
.remove_bus = pci_subdev_regulators_remove_bus,
};
@@ -1245,6 +1289,14 @@ static int brcm_pcie_suspend(struct device *dev)
return ret;
}
+ if (pcie->sr) {
+ ret = regulator_bulk_disable(pcie->sr->num_supplies, pcie->sr->supplies);
+ if (ret) {
+ dev_err(dev, "Could not turn off regulators\n");
+ reset_control_reset(pcie->rescal);
+ return ret;
+ }
+ }
clk_disable_unprepare(pcie->clk);
return 0;
@@ -1262,9 +1314,17 @@ static int brcm_pcie_resume(struct device *dev)
if (ret)
return ret;
+ if (pcie->sr) {
+ ret = regulator_bulk_enable(pcie->sr->num_supplies, pcie->sr->supplies);
+ if (ret) {
+ dev_err(dev, "Could not turn on regulators\n");
+ goto err_disable_clk;
+ }
+ }
+
ret = reset_control_reset(pcie->rescal);
if (ret)
- goto err_disable_clk;
+ goto err_regulator;
ret = brcm_phy_start(pcie);
if (ret)
@@ -1296,6 +1356,8 @@ static int brcm_pcie_resume(struct device *dev)
err_reset:
reset_control_rearm(pcie->rescal);
+err_regulator:
+ regulator_bulk_disable(pcie->sr->num_supplies, pcie->sr->supplies);
err_disable_clk:
clk_disable_unprepare(pcie->clk);
return ret;
@@ -1425,7 +1487,17 @@ static int brcm_pcie_probe(struct platform_device *pdev)
platform_set_drvdata(pdev, pcie);
- return pci_host_probe(bridge);
+ ret = pci_host_probe(bridge);
+ if (!ret && !brcm_pcie_link_up(pcie))
+ ret = -ENODEV;
+
+ if (ret) {
+ brcm_pcie_remove(pdev);
+ return ret;
+ }
+
+ return 0;
+
fail:
__brcm_pcie_remove(pcie);
return ret;
@@ -1434,8 +1506,8 @@ static int brcm_pcie_probe(struct platform_device *pdev)
MODULE_DEVICE_TABLE(of, brcm_pcie_match);
static const struct dev_pm_ops brcm_pcie_pm_ops = {
- .suspend = brcm_pcie_suspend,
- .resume = brcm_pcie_resume,
+ .suspend_noirq = brcm_pcie_suspend,
+ .resume_noirq = brcm_pcie_resume,
};
static struct platform_driver brcm_pcie_driver = {
--
2.17.1
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