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Subject[PATCH V4 4/6] PCI: tegra: Add support to enable slot regulators
Date
Add support to get regulator information of 3.3V and 12V supplies of a PCIe
slot from the respective controller's device-tree node and enable those
supplies. This is required in platforms like p2972-0000 where the supplies
to x16 slot owned by C5 controller need to be enabled before attempting to
enumerate the devices.

Signed-off-by: Vidya Sagar <vidyas@nvidia.com>
Reviewed-by: Andrew Murray <andrew.murray@arm.com>
Acked-by: Thierry Reding <treding@nvidia.com>
---
V4:
* Rebased on top of Lorenzo's pci/tegra branch

V3:
* Added a dev_err() print for failure case of tegra_pcie_get_slot_regulators() API
* Modified to make 100ms sleep valid only if at least one of the regulator handles exist

V2:
* Addressed review comments from Thierry Reding and Andrew Murray
* Handled failure case of devm_regulator_get_optional() for -ENODEV cleanly

drivers/pci/controller/dwc/pcie-tegra194.c | 83 ++++++++++++++++++++++
1 file changed, 83 insertions(+)

diff --git a/drivers/pci/controller/dwc/pcie-tegra194.c b/drivers/pci/controller/dwc/pcie-tegra194.c
index 2048ef6fad90..398ba55418ba 100644
--- a/drivers/pci/controller/dwc/pcie-tegra194.c
+++ b/drivers/pci/controller/dwc/pcie-tegra194.c
@@ -277,6 +277,8 @@ struct tegra_pcie_dw {
u32 aspm_l0s_enter_lat;

struct regulator *pex_ctl_supply;
+ struct regulator *slot_ctl_3v3;
+ struct regulator *slot_ctl_12v;

unsigned int phy_count;
struct phy **phys;
@@ -1047,6 +1049,73 @@ static void tegra_pcie_downstream_dev_to_D0(struct tegra_pcie_dw *pcie)
}
}

+static int tegra_pcie_get_slot_regulators(struct tegra_pcie_dw *pcie)
+{
+ pcie->slot_ctl_3v3 = devm_regulator_get_optional(pcie->dev, "vpcie3v3");
+ if (IS_ERR(pcie->slot_ctl_3v3)) {
+ if (PTR_ERR(pcie->slot_ctl_3v3) != -ENODEV)
+ return PTR_ERR(pcie->slot_ctl_3v3);
+
+ pcie->slot_ctl_3v3 = NULL;
+ }
+
+ pcie->slot_ctl_12v = devm_regulator_get_optional(pcie->dev, "vpcie12v");
+ if (IS_ERR(pcie->slot_ctl_12v)) {
+ if (PTR_ERR(pcie->slot_ctl_12v) != -ENODEV)
+ return PTR_ERR(pcie->slot_ctl_12v);
+
+ pcie->slot_ctl_12v = NULL;
+ }
+
+ return 0;
+}
+
+static int tegra_pcie_enable_slot_regulators(struct tegra_pcie_dw *pcie)
+{
+ int ret;
+
+ if (pcie->slot_ctl_3v3) {
+ ret = regulator_enable(pcie->slot_ctl_3v3);
+ if (ret < 0) {
+ dev_err(pcie->dev,
+ "Failed to enable 3.3V slot supply: %d\n", ret);
+ return ret;
+ }
+ }
+
+ if (pcie->slot_ctl_12v) {
+ ret = regulator_enable(pcie->slot_ctl_12v);
+ if (ret < 0) {
+ dev_err(pcie->dev,
+ "Failed to enable 12V slot supply: %d\n", ret);
+ goto fail_12v_enable;
+ }
+ }
+
+ /*
+ * According to PCI Express Card Electromechanical Specification
+ * Revision 1.1, Table-2.4, T_PVPERL (Power stable to PERST# inactive)
+ * should be a minimum of 100ms.
+ */
+ if (pcie->slot_ctl_3v3 || pcie->slot_ctl_12v)
+ msleep(100);
+
+ return 0;
+
+fail_12v_enable:
+ if (pcie->slot_ctl_3v3)
+ regulator_disable(pcie->slot_ctl_3v3);
+ return ret;
+}
+
+static void tegra_pcie_disable_slot_regulators(struct tegra_pcie_dw *pcie)
+{
+ if (pcie->slot_ctl_12v)
+ regulator_disable(pcie->slot_ctl_12v);
+ if (pcie->slot_ctl_3v3)
+ regulator_disable(pcie->slot_ctl_3v3);
+}
+
static int tegra_pcie_config_controller(struct tegra_pcie_dw *pcie,
bool en_hw_hot_rst)
{
@@ -1060,6 +1129,10 @@ static int tegra_pcie_config_controller(struct tegra_pcie_dw *pcie,
return ret;
}

+ ret = tegra_pcie_enable_slot_regulators(pcie);
+ if (ret < 0)
+ goto fail_slot_reg_en;
+
ret = regulator_enable(pcie->pex_ctl_supply);
if (ret < 0) {
dev_err(pcie->dev, "Failed to enable regulator: %d\n", ret);
@@ -1142,6 +1215,8 @@ static int tegra_pcie_config_controller(struct tegra_pcie_dw *pcie,
fail_core_clk:
regulator_disable(pcie->pex_ctl_supply);
fail_reg_en:
+ tegra_pcie_disable_slot_regulators(pcie);
+fail_slot_reg_en:
tegra_pcie_bpmp_set_ctrl_state(pcie, false);

return ret;
@@ -1174,6 +1249,8 @@ static int __deinit_controller(struct tegra_pcie_dw *pcie)
return ret;
}

+ tegra_pcie_disable_slot_regulators(pcie);
+
ret = tegra_pcie_bpmp_set_ctrl_state(pcie, false);
if (ret) {
dev_err(pcie->dev, "Failed to disable controller %d: %d\n",
@@ -1373,6 +1450,12 @@ static int tegra_pcie_dw_probe(struct platform_device *pdev)
return ret;
}

+ ret = tegra_pcie_get_slot_regulators(pcie);
+ if (ret < 0) {
+ dev_err(dev, "Failed to get slot regulators: %d\n", ret);
+ return ret;
+ }
+
pcie->pex_ctl_supply = devm_regulator_get(dev, "vddio-pex-ctl");
if (IS_ERR(pcie->pex_ctl_supply)) {
ret = PTR_ERR(pcie->pex_ctl_supply);
--
2.17.1
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