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1// SPDX-License-Identifier: (GPL-2.0+ OR BSD-3-Clause)2/* Copyright 2021 NXP3 *4 * The Integrated Endpoint Register Block (IERB) is configured by pre-boot5 * software and is supposed to be to ENETC what a NVRAM is to a 'real' PCIe6 * card. Upon FLR, values from the IERB are transferred to the ENETC PFs, and7 * are read-only in the PF memory space.8 *9 * This driver fixes up the power-on reset values for the ENETC shared FIFO,10 * such that the TX and RX allocations are sufficient for jumbo frames, and11 * that intelligent FIFO dropping is enabled before the internal data12 * structures are corrupted.13 *14 * Even though not all ports might be used on a given board, we are not15 * concerned with partitioning the FIFO, because the default values configure16 * no strict reservations, so the entire FIFO can be used by the RX of a single17 * port, or the TX of a single port.18 */19 20#include <linux/io.h>21#include <linux/mod_devicetable.h>22#include <linux/module.h>23#include <linux/pci.h>24#include <linux/platform_device.h>25#include "enetc.h"26#include "enetc_ierb.h"27 28/* IERB registers */29#define ENETC_IERB_TXMBAR(port) (((port) * 0x100) + 0x8080)30#define ENETC_IERB_RXMBER(port) (((port) * 0x100) + 0x8090)31#define ENETC_IERB_RXMBLR(port) (((port) * 0x100) + 0x8094)32#define ENETC_IERB_RXBCR(port) (((port) * 0x100) + 0x80a0)33#define ENETC_IERB_TXBCR(port) (((port) * 0x100) + 0x80a8)34#define ENETC_IERB_FMBDTR 0xa00035 36#define ENETC_RESERVED_FOR_ICM 102437 38struct enetc_ierb {39 void __iomem *regs;40};41 42static void enetc_ierb_write(struct enetc_ierb *ierb, u32 offset, u32 val)43{44 iowrite32(val, ierb->regs + offset);45}46 47int enetc_ierb_register_pf(struct platform_device *pdev,48 struct pci_dev *pf_pdev)49{50 struct enetc_ierb *ierb = platform_get_drvdata(pdev);51 int port = enetc_pf_to_port(pf_pdev);52 u16 tx_credit, rx_credit, tx_alloc;53 54 if (port < 0)55 return -ENODEV;56 57 if (!ierb)58 return -EPROBE_DEFER;59 60 /* By default, it is recommended to set the Host Transfer Agent61 * per port transmit byte credit to "1000 + max_frame_size/2".62 * The power-on reset value (1800 bytes) is rounded up to the nearest63 * 100 assuming a maximum frame size of 1536 bytes.64 */65 tx_credit = roundup(1000 + ENETC_MAC_MAXFRM_SIZE / 2, 100);66 67 /* Internal memory allocated for transmit buffering is guaranteed but68 * not reserved; i.e. if the total transmit allocation is not used,69 * then the unused portion is not left idle, it can be used for receive70 * buffering but it will be reclaimed, if required, from receive by71 * intelligently dropping already stored receive frames in the internal72 * memory to ensure that the transmit allocation is respected.73 *74 * PaTXMBAR must be set to a value larger than75 * PaTXBCR + 2 * max_frame_size + 3276 * if frame preemption is not enabled, or to77 * 2 * PaTXBCR + 2 * p_max_frame_size (pMAC maximum frame size) +78 * 2 * np_max_frame_size (eMAC maximum frame size) + 6479 * if frame preemption is enabled.80 */81 tx_alloc = roundup(2 * tx_credit + 4 * ENETC_MAC_MAXFRM_SIZE + 64, 16);82 83 /* Initial credits, in units of 8 bytes, to the Ingress Congestion84 * Manager for the maximum amount of bytes the port is allocated for85 * pending traffic.86 * It is recommended to set the initial credits to 2 times the maximum87 * frame size (2 frames of maximum size).88 */89 rx_credit = DIV_ROUND_UP(ENETC_MAC_MAXFRM_SIZE * 2, 8);90 91 enetc_ierb_write(ierb, ENETC_IERB_TXBCR(port), tx_credit);92 enetc_ierb_write(ierb, ENETC_IERB_TXMBAR(port), tx_alloc);93 enetc_ierb_write(ierb, ENETC_IERB_RXBCR(port), rx_credit);94 95 return 0;96}97EXPORT_SYMBOL(enetc_ierb_register_pf);98 99static int enetc_ierb_probe(struct platform_device *pdev)100{101 struct enetc_ierb *ierb;102 void __iomem *regs;103 104 ierb = devm_kzalloc(&pdev->dev, sizeof(*ierb), GFP_KERNEL);105 if (!ierb)106 return -ENOMEM;107 108 regs = devm_platform_get_and_ioremap_resource(pdev, 0, NULL);109 if (IS_ERR(regs))110 return PTR_ERR(regs);111 112 ierb->regs = regs;113 114 /* Free buffer depletion threshold in bytes.115 * This sets the minimum amount of free buffer memory that should be116 * maintained in the datapath sub system, and when the amount of free117 * buffer memory falls below this threshold, a depletion indication is118 * asserted, which may trigger "intelligent drop" frame releases from119 * the ingress queues in the ICM.120 * It is recommended to set the free buffer depletion threshold to 1024121 * bytes, since the ICM needs some FIFO memory for its own use.122 */123 enetc_ierb_write(ierb, ENETC_IERB_FMBDTR, ENETC_RESERVED_FOR_ICM);124 125 platform_set_drvdata(pdev, ierb);126 127 return 0;128}129 130static const struct of_device_id enetc_ierb_match[] = {131 { .compatible = "fsl,ls1028a-enetc-ierb", },132 {},133};134MODULE_DEVICE_TABLE(of, enetc_ierb_match);135 136static struct platform_driver enetc_ierb_driver = {137 .driver = {138 .name = "fsl-enetc-ierb",139 .of_match_table = enetc_ierb_match,140 },141 .probe = enetc_ierb_probe,142};143 144module_platform_driver(enetc_ierb_driver);145 146MODULE_DESCRIPTION("NXP ENETC IERB");147MODULE_LICENSE("Dual BSD/GPL");148