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From:   Sumit Gupta <sumitg@nvidia.com>
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Subject: [Patch v5 7/8] PCI: tegra194: add interconnect support in Tegra234
Date:   Thu, 30 Mar 2023 19:03:53 +0530
Message-ID: <20230330133354.714-8-sumitg@nvidia.com>
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Add support to request DRAM bandwidth with Memory Interconnect
in Tegra234 SoC. The DRAM BW required for different modes depends
on speed (Gen-1/2/3/4) and width/lanes (x1/x2/x4/x8).

Suggested-by: Manikanta Maddireddy <mmaddireddy@nvidia.com>
Signed-off-by: Sumit Gupta <sumitg@nvidia.com>
---
 drivers/pci/controller/dwc/pcie-tegra194.c | 44 ++++++++++++++++++----
 1 file changed, 36 insertions(+), 8 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-tegra194.c b/drivers/pci/controller/dwc/pcie-tegra194.c
index 09825b4a075e..89d829a946ee 100644
--- a/drivers/pci/controller/dwc/pcie-tegra194.c
+++ b/drivers/pci/controller/dwc/pcie-tegra194.c
@@ -14,6 +14,7 @@
 #include <linux/delay.h>
 #include <linux/gpio.h>
 #include <linux/gpio/consumer.h>
+#include <linux/interconnect.h>
 #include <linux/interrupt.h>
 #include <linux/iopoll.h>
 #include <linux/kernel.h>
@@ -223,6 +224,7 @@
 #define EP_STATE_ENABLED	1
 
 static const unsigned int pcie_gen_freq[] = {
+	GEN1_CORE_CLK_FREQ,   /* PCI_EXP_LNKSTA_CLS == 0; undefined */
 	GEN1_CORE_CLK_FREQ,
 	GEN2_CORE_CLK_FREQ,
 	GEN3_CORE_CLK_FREQ,
@@ -287,6 +289,7 @@ struct tegra_pcie_dw {
 	unsigned int pex_rst_irq;
 	int ep_state;
 	long link_status;
+	struct icc_path *icc_path;
 };
 
 static inline struct tegra_pcie_dw *to_tegra_pcie(struct dw_pcie *pci)
@@ -309,6 +312,27 @@ struct tegra_pcie_soc {
 	enum dw_pcie_device_mode mode;
 };
 
+static void tegra_pcie_icc_set(struct tegra_pcie_dw *pcie)
+{
+	struct dw_pcie *pci = &pcie->pci;
+	u32 val, speed, width;
+
+	val = dw_pcie_readw_dbi(pci, pcie->pcie_cap_base + PCI_EXP_LNKSTA);
+
+	speed = FIELD_GET(PCI_EXP_LNKSTA_CLS, val);
+	width = FIELD_GET(PCI_EXP_LNKSTA_NLW, val);
+
+	val = width * (PCIE_SPEED2MBS_ENC(pcie_link_speed[speed]) / BITS_PER_BYTE);
+
+	if (icc_set_bw(pcie->icc_path, MBps_to_icc(val), 0))
+		dev_err(pcie->dev, "can't set bw[%u]\n", val);
+
+	if (speed >= ARRAY_SIZE(pcie_gen_freq))
+		speed = 0;
+
+	clk_set_rate(pcie->core_clk, pcie_gen_freq[speed]);
+}
+
 static void apply_bad_link_workaround(struct dw_pcie_rp *pp)
 {
 	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
@@ -452,14 +476,12 @@ static irqreturn_t tegra_pcie_ep_irq_thread(int irq, void *arg)
 	struct tegra_pcie_dw *pcie = arg;
 	struct dw_pcie_ep *ep = &pcie->pci.ep;
 	struct dw_pcie *pci = &pcie->pci;
-	u32 val, speed;
+	u32 val;
 
 	if (test_and_clear_bit(0, &pcie->link_status))
 		dw_pcie_ep_linkup(ep);
 
-	speed = dw_pcie_readw_dbi(pci, pcie->pcie_cap_base + PCI_EXP_LNKSTA) &
-		PCI_EXP_LNKSTA_CLS;
-	clk_set_rate(pcie->core_clk, pcie_gen_freq[speed - 1]);
+	tegra_pcie_icc_set(pcie);
 
 	if (pcie->of_data->has_ltr_req_fix)
 		return IRQ_HANDLED;
@@ -945,9 +967,9 @@ static int tegra_pcie_dw_host_init(struct dw_pcie_rp *pp)
 
 static int tegra_pcie_dw_start_link(struct dw_pcie *pci)
 {
-	u32 val, offset, speed, tmp;
 	struct tegra_pcie_dw *pcie = to_tegra_pcie(pci);
 	struct dw_pcie_rp *pp = &pci->pp;
+	u32 val, offset, tmp;
 	bool retry = true;
 
 	if (pcie->of_data->mode == DW_PCIE_EP_TYPE) {
@@ -1018,9 +1040,7 @@ static int tegra_pcie_dw_start_link(struct dw_pcie *pci)
 		goto retry_link;
 	}
 
-	speed = dw_pcie_readw_dbi(pci, pcie->pcie_cap_base + PCI_EXP_LNKSTA) &
-		PCI_EXP_LNKSTA_CLS;
-	clk_set_rate(pcie->core_clk, pcie_gen_freq[speed - 1]);
+	tegra_pcie_icc_set(pcie);
 
 	tegra_pcie_enable_interrupts(pp);
 
@@ -2224,6 +2244,14 @@ static int tegra_pcie_dw_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, pcie);
 
+	pcie->icc_path = devm_of_icc_get(&pdev->dev, "write");
+	ret = PTR_ERR_OR_ZERO(pcie->icc_path);
+	if (ret) {
+		tegra_bpmp_put(pcie->bpmp);
+		dev_err_probe(&pdev->dev, ret, "failed to get write interconnect\n");
+		return ret;
+	}
+
 	switch (pcie->of_data->mode) {
 	case DW_PCIE_RC_TYPE:
 		ret = devm_request_irq(dev, pp->irq, tegra_pcie_rp_irq_handler,
-- 
2.17.1