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Message-Id: <20250903-pci-pwrctrl-perst-v2-5-2d461ed0e061@oss.qualcomm.com>
Date: Wed, 03 Sep 2025 12:43:27 +0530
From: Manivannan Sadhasivam via B4 Relay <devnull+manivannan.sadhasivam.oss.qualcomm.com@...nel.org>
To: Manivannan Sadhasivam <mani@...nel.org>,
Lorenzo Pieralisi <lpieralisi@...nel.org>,
Krzysztof Wilczyński <kwilczynski@...nel.org>,
Rob Herring <robh@...nel.org>, Bjorn Helgaas <bhelgaas@...gle.com>,
Bartosz Golaszewski <brgl@...ev.pl>, Saravana Kannan <saravanak@...gle.com>
Cc: linux-pci@...r.kernel.org, linux-arm-msm@...r.kernel.org,
linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>,
Brian Norris <briannorris@...omium.org>,
Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>
Subject: [PATCH v2 5/5] PCI: qcom: Allow pwrctrl core to toggle PERST# for
new DT binding
From: Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>
If the platform is using the new DT binding, let the pwrctrl core toggle
PERST# for the device. This is achieved by populating the
'pci_host_bridge::toggle_perst' callback with qcom_pcie_toggle_perst().
qcom_pcie_toggle_perst() will find the PERST# GPIO descriptor associated
with the supplied 'device_node' and toggles PERST#. If PERST# is not found
in the supplied node, the function will look for PERST# in the parent node
as a fallback. This is needed since PERST# won't be available in the
endpoint node as per the DT binding.
Note that the driver still asserts PERST# during the controller
initialization as it is needed as per the hardware documentation. Apart
from that, the driver wouldn't touch PERST# for the new binding.
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>
---
drivers/pci/controller/dwc/pcie-qcom.c | 89 +++++++++++++++++++++++++++++-----
1 file changed, 78 insertions(+), 11 deletions(-)
diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index 78355d12f10d263a0bb052e24c1e2d5e8f68603d..3c5c65d7d97cac186e1b671f80ba7296ad226d68 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -276,6 +276,7 @@ struct qcom_pcie_port {
struct qcom_pcie_perst {
struct list_head list;
struct gpio_desc *desc;
+ struct device_node *np;
};
struct qcom_pcie {
@@ -298,11 +299,50 @@ struct qcom_pcie {
#define to_qcom_pcie(x) dev_get_drvdata((x)->dev)
-static void qcom_perst_assert(struct qcom_pcie *pcie, bool assert)
+static struct gpio_desc *qcom_find_perst(struct qcom_pcie *pcie, struct device_node *np)
+{
+ struct qcom_pcie_perst *perst;
+
+ list_for_each_entry(perst, &pcie->perst, list) {
+ if (np == perst->np)
+ return perst->desc;
+ }
+
+ return NULL;
+}
+
+static void qcom_toggle_perst_per_device(struct qcom_pcie *pcie,
+ struct device_node *np, bool assert)
+{
+ int val = assert ? 1 : 0;
+ struct gpio_desc *perst;
+
+ perst = qcom_find_perst(pcie, np);
+ if (perst)
+ goto toggle_perst;
+
+ /*
+ * If PERST# is not available in the current node, try the parent. This
+ * fallback is needed if the current node belongs to an endpoint or
+ * switch upstream port.
+ */
+ if (np->parent)
+ perst = qcom_find_perst(pcie, np->parent);
+
+toggle_perst:
+ /* gpiod* APIs handle NULL gpio_desc gracefully. So no need to check. */
+ gpiod_set_value_cansleep(perst, val);
+}
+
+static void qcom_perst_reset(struct qcom_pcie *pcie, struct device_node *np,
+ bool assert)
{
struct qcom_pcie_perst *perst;
int val = assert ? 1 : 0;
+ if (np)
+ return qcom_toggle_perst_per_device(pcie, np, assert);
+
if (list_empty(&pcie->perst))
gpiod_set_value_cansleep(pcie->reset, val);
@@ -310,22 +350,34 @@ static void qcom_perst_assert(struct qcom_pcie *pcie, bool assert)
gpiod_set_value_cansleep(perst->desc, val);
}
-static void qcom_ep_reset_assert(struct qcom_pcie *pcie)
+static void qcom_ep_reset_assert(struct qcom_pcie *pcie, struct device_node *np)
{
- qcom_perst_assert(pcie, true);
+ qcom_perst_reset(pcie, np, true);
usleep_range(PERST_DELAY_US, PERST_DELAY_US + 500);
}
-static void qcom_ep_reset_deassert(struct qcom_pcie *pcie)
+static void qcom_ep_reset_deassert(struct qcom_pcie *pcie,
+ struct device_node *np)
{
struct dw_pcie_rp *pp = &pcie->pci->pp;
msleep(PCIE_T_PVPERL_MS);
- qcom_perst_assert(pcie, false);
+ qcom_perst_reset(pcie, np, false);
if (!pp->use_linkup_irq)
msleep(PCIE_RESET_CONFIG_WAIT_MS);
}
+static void qcom_pcie_toggle_perst(struct pci_host_bridge *bridge,
+ struct device_node *np, bool assert)
+{
+ struct qcom_pcie *pcie = dev_get_drvdata(bridge->dev.parent);
+
+ if (assert)
+ qcom_ep_reset_assert(pcie, np);
+ else
+ qcom_ep_reset_deassert(pcie, np);
+}
+
static int qcom_pcie_start_link(struct dw_pcie *pci)
{
struct qcom_pcie *pcie = to_qcom_pcie(pci);
@@ -1320,7 +1372,7 @@ static int qcom_pcie_host_init(struct dw_pcie_rp *pp)
struct qcom_pcie *pcie = to_qcom_pcie(pci);
int ret;
- qcom_ep_reset_assert(pcie);
+ qcom_ep_reset_assert(pcie, NULL);
ret = pcie->cfg->ops->init(pcie);
if (ret)
@@ -1336,7 +1388,13 @@ static int qcom_pcie_host_init(struct dw_pcie_rp *pp)
goto err_disable_phy;
}
- qcom_ep_reset_deassert(pcie);
+ /*
+ * Only deassert PERST# for all devices here if legacy binding is used.
+ * For the new binding, pwrctrl driver is expected to toggle PERST# for
+ * individual devices.
+ */
+ if (list_empty(&pcie->perst))
+ qcom_ep_reset_deassert(pcie, NULL);
if (pcie->cfg->ops->config_sid) {
ret = pcie->cfg->ops->config_sid(pcie);
@@ -1344,10 +1402,12 @@ static int qcom_pcie_host_init(struct dw_pcie_rp *pp)
goto err_assert_reset;
}
+ pci->pp.bridge->toggle_perst = qcom_pcie_toggle_perst;
+
return 0;
err_assert_reset:
- qcom_ep_reset_assert(pcie);
+ qcom_ep_reset_assert(pcie, NULL);
err_disable_phy:
qcom_pcie_phy_power_off(pcie);
err_deinit:
@@ -1361,7 +1421,7 @@ static void qcom_pcie_host_deinit(struct dw_pcie_rp *pp)
struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
struct qcom_pcie *pcie = to_qcom_pcie(pci);
- qcom_ep_reset_assert(pcie);
+ qcom_ep_reset_assert(pcie, NULL);
qcom_pcie_phy_power_off(pcie);
pcie->cfg->ops->deinit(pcie);
}
@@ -1740,6 +1800,9 @@ static int qcom_pcie_parse_perst(struct qcom_pcie *pcie,
return -ENOMEM;
perst->desc = reset;
+ /* Increase the refcount to make sure 'np' is valid till it is stored */
+ of_node_get(np);
+ perst->np = np;
list_add_tail(&perst->list, &pcie->perst);
parse_child_node:
@@ -1803,8 +1866,10 @@ static int qcom_pcie_parse_ports(struct qcom_pcie *pcie)
list_del(&port->list);
}
- list_for_each_entry_safe(perst, tmp_perst, &pcie->perst, list)
+ list_for_each_entry_safe(perst, tmp_perst, &pcie->perst, list) {
+ of_node_put(perst->np);
list_del(&perst->list);
+ }
return ret;
}
@@ -2044,8 +2109,10 @@ static int qcom_pcie_probe(struct platform_device *pdev)
qcom_pcie_phy_exit(pcie);
list_for_each_entry_safe(port, tmp_port, &pcie->ports, list)
list_del(&port->list);
- list_for_each_entry_safe(perst, tmp_perst, &pcie->perst, list)
+ list_for_each_entry_safe(perst, tmp_perst, &pcie->perst, list) {
+ of_node_put(perst->np);
list_del(&perst->list);
+ }
err_pm_runtime_put:
pm_runtime_put(dev);
pm_runtime_disable(dev);
--
2.45.2
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