[PATCH v2 05/10] PCI: qcom: Add support for PCIe bus bw scaling

[Krishna Chaitanya Chundru]

QCOM PCIe controllers need to disable ASPM before initiating link
re-train. So as part of pre_bw_scale() disable ASPM and as part of
post_scale_bus_bw() enable ASPM back.

Update ICC & OPP votes based on the requested speed so that RPMh votes
get updated based on the speed.

Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@xxxxxxxxxxxxxxxx>
---
 drivers/pci/controller/dwc/pcie-qcom.c | 49 ++++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)

diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index b66c413f1e2b..a68e62422ff7 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -1328,10 +1328,59 @@ static int qcom_pcie_set_icc_opp(struct qcom_pcie *pcie, int speed, int width)
 	return ret;
 }
 
+static int qcom_pcie_scale_bw(struct dw_pcie_rp *pp, int speed)
+{
+	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
+	struct qcom_pcie *pcie = to_qcom_pcie(pci);
+	u32 offset, status, width;
+
+	offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
+	status = readw(pci->dbi_base + offset + PCI_EXP_LNKSTA);
+
+	width = FIELD_GET(PCI_EXP_LNKSTA_NLW, status);
+
+	return qcom_pcie_set_icc_opp(pcie, speed, width);
+}
+
+static int qcom_pcie_enable_disable_aspm(struct pci_dev *pdev, void *userdata)
+{
+	bool *enable = userdata;
+
+	/*
+	 * QCOM controllers doesn't support link re-train with ASPM enabled.
+	 * Disable ASPM as part of pre_bus_bw() and enable them back as
+	 * part of post_bus_bw().
+	 */
+	if (*enable)
+		pci_enable_link_state_locked(pdev, PCIE_LINK_STATE_ALL);
+	else
+		pci_disable_link_state_locked(pdev, PCIE_LINK_STATE_ALL);
+
+	return 0;
+}
+
+static void qcom_pcie_host_post_scale_bus_bw(struct dw_pcie_rp *pp, int current_speed)
+{
+	bool enable = true;
+
+	pci_walk_bus(pp->bridge->bus, qcom_pcie_enable_disable_aspm, &enable);
+	qcom_pcie_scale_bw(pp, current_speed);
+}
+
+static int qcom_pcie_host_pre_scale_bus_bw(struct dw_pcie_rp *pp, int target_speed)
+{
+	bool enable = false;
+
+	pci_walk_bus(pp->bridge->bus, qcom_pcie_enable_disable_aspm, &enable);
+	return qcom_pcie_scale_bw(pp, target_speed);
+}
+
 static const struct dw_pcie_host_ops qcom_pcie_dw_ops = {
 	.init		= qcom_pcie_host_init,
 	.deinit		= qcom_pcie_host_deinit,
 	.post_init	= qcom_pcie_host_post_init,
+	.pre_scale_bus_bw	= qcom_pcie_host_pre_scale_bus_bw,
+	.post_scale_bus_bw	= qcom_pcie_host_post_scale_bus_bw,
 };
 
 /* Qcom IP rev.: 2.1.0	Synopsys IP rev.: 4.01a */

-- 
2.34.1