1 // SPDX-License-Identifier: (GPL-2.0+ OR BSD-3-Clause) 2 /* Copyright 2021 NXP 3 * 4 * The Integrated Endpoint Register Block (IERB) is configured by pre-boot 5 * software and is supposed to be to ENETC what a NVRAM is to a 'real' PCIe 6 * card. Upon FLR, values from the IERB are transferred to the ENETC PFs, and 7 * 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, and 11 * that intelligent FIFO dropping is enabled before the internal data 12 * structures are corrupted. 13 * 14 * Even though not all ports might be used on a given board, we are not 15 * concerned with partitioning the FIFO, because the default values configure 16 * no strict reservations, so the entire FIFO can be used by the RX of a single 17 * port, or the TX of a single port. 18 */ 19 20 #include <linux/io.h> 21 #include <linux/module.h> 22 #include <linux/of_device.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 0xa000 35 36 #define ENETC_RESERVED_FOR_ICM 1024 37 38 struct enetc_ierb { 39 void __iomem *regs; 40 }; 41 42 static void enetc_ierb_write(struct enetc_ierb *ierb, u32 offset, u32 val) 43 { 44 iowrite32(val, ierb->regs + offset); 45 } 46 47 int 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 Agent 61 * per port transmit byte credit to "1000 + max_frame_size/2". 62 * The power-on reset value (1800 bytes) is rounded up to the nearest 63 * 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 but 68 * 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 receive 70 * buffering but it will be reclaimed, if required, from receive by 71 * intelligently dropping already stored receive frames in the internal 72 * memory to ensure that the transmit allocation is respected. 73 * 74 * PaTXMBAR must be set to a value larger than 75 * PaTXBCR + 2 * max_frame_size + 32 76 * if frame preemption is not enabled, or to 77 * 2 * PaTXBCR + 2 * p_max_frame_size (pMAC maximum frame size) + 78 * 2 * np_max_frame_size (eMAC maximum frame size) + 64 79 * 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 Congestion 84 * Manager for the maximum amount of bytes the port is allocated for 85 * pending traffic. 86 * It is recommended to set the initial credits to 2 times the maximum 87 * 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 } 97 EXPORT_SYMBOL(enetc_ierb_register_pf); 98 99 static 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 be 116 * maintained in the datapath sub system, and when the amount of free 117 * buffer memory falls below this threshold, a depletion indication is 118 * asserted, which may trigger "intelligent drop" frame releases from 119 * the ingress queues in the ICM. 120 * It is recommended to set the free buffer depletion threshold to 1024 121 * 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 } 129 130 static const struct of_device_id enetc_ierb_match[] = { 131 { .compatible = "fsl,ls1028a-enetc-ierb", }, 132 {}, 133 }; 134 MODULE_DEVICE_TABLE(of, enetc_ierb_match); 135 136 static 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 }; 143 144 module_platform_driver(enetc_ierb_driver); 145 146 MODULE_DESCRIPTION("NXP ENETC IERB"); 147 MODULE_LICENSE("Dual BSD/GPL"); 148