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[ Upstream commit37bf0f4e39] Add lane equalization setting for 8.0 GT/s and 32.0 GT/s to enhance link stability and avoid AER Correctable Errors reported on some platforms (eg. SA8775P). 8.0 GT/s, 16.0 GT/s and 32.0 GT/s require the same equalization setting. This setting is programmed into a group of shadow registers, which can be switched to configure equalization for different speeds by writing 00b, 01b and 10b to `RATE_SHADOW_SEL`. Hence, program equalization registers in a loop using link speed as index, so that equalization setting can be programmed for 8.0 GT/s, 16.0 GT/s and 32.0 GT/s. Fixes:489f14be0e("arm64: dts: qcom: sa8775p: Add pcie0 and pcie1 nodes") Co-developed-by: Qiang Yu <qiang.yu@oss.qualcomm.com> Signed-off-by: Qiang Yu <qiang.yu@oss.qualcomm.com> Signed-off-by: Ziyue Zhang <ziyue.zhang@oss.qualcomm.com> [mani: wrapped the warning to fit 100 columns, used post-increment for loop] Signed-off-by: Manivannan Sadhasivam <mani@kernel.org> Link: https://patch.msgid.link/20250904065225.1762793-2-ziyue.zhang@oss.qualcomm.com Signed-off-by: Sasha Levin <sashal@kernel.org>
89 lines
3.0 KiB
C
89 lines
3.0 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (c) 2024 Qualcomm Innovation Center, Inc. All rights reserved.
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*/
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#include <linux/pci.h>
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#include "pcie-designware.h"
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#include "pcie-qcom-common.h"
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void qcom_pcie_common_set_equalization(struct dw_pcie *pci)
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{
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struct device *dev = pci->dev;
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u32 reg;
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u16 speed;
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/*
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* GEN3_RELATED_OFF register is repurposed to apply equalization
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* settings at various data transmission rates through registers namely
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* GEN3_EQ_*. The RATE_SHADOW_SEL bit field of GEN3_RELATED_OFF
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* determines the data rate for which these equalization settings are
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* applied.
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*/
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for (speed = PCIE_SPEED_8_0GT; speed <= pcie_link_speed[pci->max_link_speed]; speed++) {
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if (speed > PCIE_SPEED_32_0GT) {
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dev_warn(dev, "Skipped equalization settings for unsupported data rate\n");
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break;
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}
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reg = dw_pcie_readl_dbi(pci, GEN3_RELATED_OFF);
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reg &= ~GEN3_RELATED_OFF_GEN3_ZRXDC_NONCOMPL;
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reg &= ~GEN3_RELATED_OFF_RATE_SHADOW_SEL_MASK;
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reg |= FIELD_PREP(GEN3_RELATED_OFF_RATE_SHADOW_SEL_MASK,
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speed - PCIE_SPEED_8_0GT);
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dw_pcie_writel_dbi(pci, GEN3_RELATED_OFF, reg);
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reg = dw_pcie_readl_dbi(pci, GEN3_EQ_FB_MODE_DIR_CHANGE_OFF);
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reg &= ~(GEN3_EQ_FMDC_T_MIN_PHASE23 |
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GEN3_EQ_FMDC_N_EVALS |
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GEN3_EQ_FMDC_MAX_PRE_CUSROR_DELTA |
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GEN3_EQ_FMDC_MAX_POST_CUSROR_DELTA);
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reg |= FIELD_PREP(GEN3_EQ_FMDC_T_MIN_PHASE23, 0x1) |
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FIELD_PREP(GEN3_EQ_FMDC_N_EVALS, 0xd) |
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FIELD_PREP(GEN3_EQ_FMDC_MAX_PRE_CUSROR_DELTA, 0x5) |
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FIELD_PREP(GEN3_EQ_FMDC_MAX_POST_CUSROR_DELTA, 0x5);
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dw_pcie_writel_dbi(pci, GEN3_EQ_FB_MODE_DIR_CHANGE_OFF, reg);
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reg = dw_pcie_readl_dbi(pci, GEN3_EQ_CONTROL_OFF);
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reg &= ~(GEN3_EQ_CONTROL_OFF_FB_MODE |
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GEN3_EQ_CONTROL_OFF_PHASE23_EXIT_MODE |
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GEN3_EQ_CONTROL_OFF_FOM_INC_INITIAL_EVAL |
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GEN3_EQ_CONTROL_OFF_PSET_REQ_VEC);
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dw_pcie_writel_dbi(pci, GEN3_EQ_CONTROL_OFF, reg);
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}
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}
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EXPORT_SYMBOL_GPL(qcom_pcie_common_set_equalization);
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void qcom_pcie_common_set_16gt_lane_margining(struct dw_pcie *pci)
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{
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u32 reg;
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reg = dw_pcie_readl_dbi(pci, GEN4_LANE_MARGINING_1_OFF);
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reg &= ~(MARGINING_MAX_VOLTAGE_OFFSET |
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MARGINING_NUM_VOLTAGE_STEPS |
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MARGINING_MAX_TIMING_OFFSET |
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MARGINING_NUM_TIMING_STEPS);
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reg |= FIELD_PREP(MARGINING_MAX_VOLTAGE_OFFSET, 0x24) |
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FIELD_PREP(MARGINING_NUM_VOLTAGE_STEPS, 0x78) |
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FIELD_PREP(MARGINING_MAX_TIMING_OFFSET, 0x32) |
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FIELD_PREP(MARGINING_NUM_TIMING_STEPS, 0x10);
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dw_pcie_writel_dbi(pci, GEN4_LANE_MARGINING_1_OFF, reg);
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reg = dw_pcie_readl_dbi(pci, GEN4_LANE_MARGINING_2_OFF);
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reg |= MARGINING_IND_ERROR_SAMPLER |
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MARGINING_SAMPLE_REPORTING_METHOD |
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MARGINING_IND_LEFT_RIGHT_TIMING |
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MARGINING_VOLTAGE_SUPPORTED;
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reg &= ~(MARGINING_IND_UP_DOWN_VOLTAGE |
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MARGINING_MAXLANES |
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MARGINING_SAMPLE_RATE_TIMING |
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MARGINING_SAMPLE_RATE_VOLTAGE);
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reg |= FIELD_PREP(MARGINING_MAXLANES, pci->num_lanes) |
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FIELD_PREP(MARGINING_SAMPLE_RATE_TIMING, 0x3f) |
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FIELD_PREP(MARGINING_SAMPLE_RATE_VOLTAGE, 0x3f);
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dw_pcie_writel_dbi(pci, GEN4_LANE_MARGINING_2_OFF, reg);
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}
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EXPORT_SYMBOL_GPL(qcom_pcie_common_set_16gt_lane_margining);
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