[PATCH RFC 3/3] PCI: qcom: Allow pwrctrl framework to control PERST#

[Manivannan Sadhasivam <mani@kernel.org>]

Since the Qcom platforms rely on pwrctrl framework to control the power
supplies, allow it to control PERST# also. PERST# should be toggled during
the power-on and power-off scenarios.

But the controller driver still need to assert PERST# during the controller
initialization. So only skip the deassert if pwrctrl usage is detected. The
pwrctrl framework will deassert PERST# after turning on the supplies.

The usage of pwrctrl framework is detected based on the new DT binding
i.e., with the presence of PERST# and PHY properties in the Root Port node
instead of the host bridge node.

When the legacy binding is used, PERST# is only controlled by the
controller driver since it is not reliable to detect whether pwrctrl is
used or not. So the legacy platforms are untouched by this commit.

Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
---
 drivers/pci/controller/dwc/pcie-designware-host.c |  1 +
 drivers/pci/controller/dwc/pcie-designware.h      |  1 +
 drivers/pci/controller/dwc/pcie-qcom.c            | 26 ++++++++++++++++++++++-
 3 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
index af6c91ec7312bab6c6e5ad35b051d0f452fe7b8d..e45f53bb135a75963318666a479eb6d9582f30eb 100644
--- a/drivers/pci/controller/dwc/pcie-designware-host.c
+++ b/drivers/pci/controller/dwc/pcie-designware-host.c
@@ -492,6 +492,7 @@ int dw_pcie_host_init(struct dw_pcie_rp *pp)
 		return -ENOMEM;
 
 	pp->bridge = bridge;
+	bridge->perst = pp->perst;
 
 	ret = dw_pcie_host_get_resources(pp);
 	if (ret)
diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
index 4165c49a0a5059cab92dee3c47f8024af9d840bd..7b28f76ebf6a2de8781746eba43a8e3ad9a5cbb2 100644
--- a/drivers/pci/controller/dwc/pcie-designware.h
+++ b/drivers/pci/controller/dwc/pcie-designware.h
@@ -430,6 +430,7 @@ struct dw_pcie_rp {
 	struct resource		*msg_res;
 	bool			use_linkup_irq;
 	struct pci_eq_presets	presets;
+	struct gpio_desc	**perst;
 };
 
 struct dw_pcie_ep_ops {
diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index 620ac7cf09472b84c37e83ee3ce40e94a1d9d878..61e1d0d6469030c549328ab4d8c65d5377d525e3 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -313,6 +313,11 @@ static void qcom_ep_reset_assert(struct qcom_pcie *pcie)
 
 static void qcom_ep_reset_deassert(struct qcom_pcie *pcie)
 {
+	struct dw_pcie_rp *pp = &pcie->pci->pp;
+
+	if (pp->perst)
+		return;
+
 	/* Ensure that PERST has been asserted for at least 100 ms */
 	msleep(PCIE_T_PVPERL_MS);
 	qcom_perst_assert(pcie, false);
@@ -1701,11 +1706,12 @@ static const struct pci_ecam_ops pci_qcom_ecam_ops = {
 
 static int qcom_pcie_parse_port(struct qcom_pcie *pcie, struct device_node *node)
 {
+	struct dw_pcie_rp *pp = &pcie->pci->pp;
 	struct device *dev = pcie->pci->dev;
 	struct qcom_pcie_port *port;
 	struct gpio_desc *reset;
 	struct phy *phy;
-	int ret;
+	int ret, devfn;
 
 	reset = devm_fwnode_gpiod_get(dev, of_fwnode_handle(node),
 				      "reset", GPIOD_OUT_HIGH, "PERST#");
@@ -1724,6 +1730,12 @@ static int qcom_pcie_parse_port(struct qcom_pcie *pcie, struct device_node *node
 	if (ret)
 		return ret;
 
+	devfn = of_pci_get_devfn(node);
+	if (devfn < 0)
+		return -ENOENT;
+
+	pp->perst[PCI_SLOT(devfn)] = reset;
+
 	port->reset = reset;
 	port->phy = phy;
 	INIT_LIST_HEAD(&port->list);
@@ -1734,10 +1746,20 @@ static int qcom_pcie_parse_port(struct qcom_pcie *pcie, struct device_node *node
 
 static int qcom_pcie_parse_ports(struct qcom_pcie *pcie)
 {
+	struct dw_pcie_rp *pp = &pcie->pci->pp;
 	struct device *dev = pcie->pci->dev;
 	struct qcom_pcie_port *port, *tmp;
+	int child_cnt;
 	int ret = -ENOENT;
 
+	child_cnt = of_get_available_child_count(dev->of_node);
+	if (!child_cnt)
+		return ret;
+
+	pp->perst = kcalloc(child_cnt, sizeof(struct gpio_desc *), GFP_KERNEL);
+	if (!pp->perst)
+		return -ENOMEM;
+
 	for_each_available_child_of_node_scoped(dev->of_node, of_port) {
 		ret = qcom_pcie_parse_port(pcie, of_port);
 		if (ret)
@@ -1747,6 +1769,7 @@ static int qcom_pcie_parse_ports(struct qcom_pcie *pcie)
 	return ret;
 
 err_port_del:
+	kfree(pp->perst);
 	list_for_each_entry_safe(port, tmp, &pcie->ports, list)
 		list_del(&port->list);
 
@@ -1984,6 +2007,7 @@ static int qcom_pcie_probe(struct platform_device *pdev)
 	dw_pcie_host_deinit(pp);
 err_phy_exit:
 	qcom_pcie_phy_exit(pcie);
+	kfree(pp->perst);
 	list_for_each_entry_safe(port, tmp, &pcie->ports, list)
 		list_del(&port->list);
 err_pm_runtime_put:

-- 
2.45.2