Re: [PATCH v3 3/3] PCI: qcom-ep: Add ICC bandwidth voting support

From: Krishna Chaitanya Chundru
Date: Wed Jun 14 2023 - 10:29:32 EST


On 6/9/2023 9:56 PM, Dmitry Baryshkov wrote:
On Fri, 9 Jun 2023 at 14:47, Krishna chaitanya chundru
<quic_krichai@xxxxxxxxxxx> wrote:
Add support to vote for ICC bandwidth based on the link speed and width.

This patch is inspired from pcie-qcom driver to add basic interconnect
support.

Link: https://lore.kernel.org/all/20221102090705.23634-1-johan+linaro@xxxxxxxxxx/
This link should be a part of the cover letter, not the commit msg. If
you want to refer to the previous commits, please use the standard
reference: commit abcdefabc ("PCI: qcom: Make foo and bar").
done
Signed-off-by: Krishna chaitanya chundru <quic_krichai@xxxxxxxxxxx>
---
drivers/pci/controller/dwc/pcie-qcom-ep.c | 68 +++++++++++++++++++++++++++++++
1 file changed, 68 insertions(+)

diff --git a/drivers/pci/controller/dwc/pcie-qcom-ep.c b/drivers/pci/controller/dwc/pcie-qcom-ep.c
index 19b3283..baf831f 100644
--- a/drivers/pci/controller/dwc/pcie-qcom-ep.c
+++ b/drivers/pci/controller/dwc/pcie-qcom-ep.c
@@ -13,6 +13,7 @@
#include <linux/debugfs.h>
#include <linux/delay.h>
#include <linux/gpio/consumer.h>
+#include <linux/interconnect.h>
#include <linux/mfd/syscon.h>
#include <linux/phy/pcie.h>
#include <linux/phy/phy.h>
@@ -28,6 +29,7 @@
#define PARF_SYS_CTRL 0x00
#define PARF_DB_CTRL 0x10
#define PARF_PM_CTRL 0x20
+#define PARF_PM_STTS 0x24
#define PARF_MHI_CLOCK_RESET_CTRL 0x174
#define PARF_MHI_BASE_ADDR_LOWER 0x178
#define PARF_MHI_BASE_ADDR_UPPER 0x17c
@@ -128,6 +130,9 @@
/* DBI register fields */
#define DBI_CON_STATUS_POWER_STATE_MASK GENMASK(1, 0)

+#define DBI_LINKCTRLSTATUS 0x80
+#define DBI_LINKCTRLSTATUS_SHIFT 16
+
#define XMLH_LINK_UP 0x400
#define CORE_RESET_TIME_US_MIN 1000
#define CORE_RESET_TIME_US_MAX 1005
@@ -178,6 +183,8 @@ struct qcom_pcie_ep {
struct phy *phy;
struct dentry *debugfs;

+ struct icc_path *icc_mem;
+
struct clk_bulk_data *clks;
int num_clks;

@@ -253,9 +260,51 @@ static void qcom_pcie_dw_stop_link(struct dw_pcie *pci)
disable_irq(pcie_ep->perst_irq);
}

+static void qcom_pcie_ep_icc_update(struct qcom_pcie_ep *pcie_ep)
+{
+ struct dw_pcie *pci = &pcie_ep->pci;
+ u32 offset, status, bw;
+ int speed, width;
+ int ret;
+
+ if (!pcie_ep->icc_mem)
+ return;
+
+ offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
+ status = readw(pci->dbi_base + offset + PCI_EXP_LNKSTA);
+
+ speed = FIELD_GET(PCI_EXP_LNKSTA_CLS, status);
+ width = FIELD_GET(PCI_EXP_LNKSTA_NLW, status);
+
+ switch (speed) {
+ case 1:
+ bw = MBps_to_icc(250); /* BW for GEN1 per lane: 250MBps */
Please extract these constants to the defines. This would save you
from duplicating 250 below.
done
+ break;
+ case 2:
+ bw = MBps_to_icc(500); /* BW for GEN2 per lane: 500MBps */
+ break;
+ case 3:
+ bw = MBps_to_icc(985); /* BW for GEN3 per lane: 985MBps */
+ break;
+ default:
+ WARN_ON_ONCE(1);
+ fallthrough;
+ case 4:
+ bw = MBps_to_icc(1969); /* BW for GEN4 per lane:1969MBps */
+ break;
+ }
+
+ ret = icc_set_bw(pcie_ep->icc_mem, 0, width * bw);
+ if (ret) {
+ dev_err(pci->dev, "failed to set interconnect bandwidth: %d\n",
+ ret);
+ }
+}
+
static int qcom_pcie_enable_resources(struct qcom_pcie_ep *pcie_ep)
{
int ret;
+ struct dw_pcie *pci = &pcie_ep->pci;

ret = clk_bulk_prepare_enable(pcie_ep->num_clks, pcie_ep->clks);
if (ret)
@@ -277,6 +326,20 @@ static int qcom_pcie_enable_resources(struct qcom_pcie_ep *pcie_ep)
if (ret)
goto err_phy_exit;

+ /*
+ * Some Qualcomm platforms require interconnect bandwidth constraints
+ * to be set before enabling interconnect clocks.
+ *
+ * Set an initial average bandwidth corresponding to GEN1x1(250 MBps)
+ * for the pcie to mem path.
+ */
+ ret = icc_set_bw(pcie_ep->icc_mem, 0, MBps_to_icc(250));
+ if (ret) {
+ dev_err(pci->dev, "failed to set interconnect bandwidth: %d\n",
+ ret);
+ goto err_phy_exit;
+ }
+
return 0;

err_phy_exit:
@@ -550,6 +613,10 @@ static int qcom_pcie_ep_get_resources(struct platform_device *pdev,
if (IS_ERR(pcie_ep->phy))
ret = PTR_ERR(pcie_ep->phy);

+ pcie_ep->icc_mem = devm_of_icc_get(dev, "pcie-mem");
+ if (IS_ERR(pcie_ep->icc_mem))
+ ret = PTR_ERR(pcie_ep->icc_mem);
+
return ret;
}

@@ -572,6 +639,7 @@ static irqreturn_t qcom_pcie_ep_global_irq_thread(int irq, void *data)
} else if (FIELD_GET(PARF_INT_ALL_BME, status)) {
dev_dbg(dev, "Received BME event. Link is enabled!\n");
pcie_ep->link_status = QCOM_PCIE_EP_LINK_ENABLED;
+ qcom_pcie_ep_icc_update(pcie_ep);
} else if (FIELD_GET(PARF_INT_ALL_PM_TURNOFF, status)) {
dev_dbg(dev, "Received PM Turn-off event! Entering L23\n");
val = readl_relaxed(pcie_ep->parf + PARF_PM_CTRL);
--
2.7.4