From 2341a0705164e94d0874572505b60680fdbe631f Mon Sep 17 00:00:00 2001
From: dzwdz
Date: Wed, 17 Aug 2022 12:49:34 +0200
Subject: amd64: rtl8139 driver with basic rx support

---
 src/kernel/arch/amd64/driver/rtl8139.c | 150 +++++++++++++++++++++++++++++++++
 1 file changed, 150 insertions(+)
 create mode 100644 src/kernel/arch/amd64/driver/rtl8139.c

(limited to 'src/kernel/arch/amd64/driver/rtl8139.c')

diff --git a/src/kernel/arch/amd64/driver/rtl8139.c b/src/kernel/arch/amd64/driver/rtl8139.c
new file mode 100644
index 0000000..d9e5af0
--- /dev/null
+++ b/src/kernel/arch/amd64/driver/rtl8139.c
@@ -0,0 +1,150 @@
+#include <kernel/arch/amd64/driver/rtl8139.h>
+#include <kernel/arch/amd64/pci.h>
+#include <kernel/arch/amd64/port_io.h>
+#include <kernel/mem/virt.h>
+#include <kernel/panic.h>
+#include <kernel/vfs/request.h>
+#include <stdbool.h>
+
+static void accept(struct vfs_request *req);
+static struct vfs_backend backend = BACKEND_KERN(accept);
+static struct vfs_request *blocked_on = NULL;
+
+
+enum {
+	MAC = 0,
+	RBSTART = 0x30,
+	CMD = 0x37,
+	CAPR = 0x38,
+	CBR = 0x3A,
+	INTRMASK = 0x3C,
+	INTRSTATUS = 0x3E,
+	RCR = 0x44, /* receive configure */
+	CONFIG1 = 0x52,
+};
+
+static uint16_t iobase;
+
+#define buflen_shift 3
+#define rxbuf_baselen ((8 * 1024) << buflen_shift)
+static char rxbuf[rxbuf_baselen + 16 + 1500];
+static size_t rxpos;
+
+static void rx_irq_enable(bool v) {
+	uint16_t mask = 1 | 4; /* rx/tx ok */
+	port_out16(iobase + INTRMASK, v ? mask : 0);
+}
+
+void rtl8139_init(uint32_t bdf) {
+	if (iobase) panic_unimplemented(); /* multiple devices */
+	iobase = pcicfg_iobase(bdf);
+
+	/* also includes the status, because i have only implemented w32 */
+	uint32_t cmd = pcicfg_r32(bdf, PCICFG_CMD);
+	cmd |= 1 << 2; /* bus mastering */
+	pcicfg_w32(bdf, PCICFG_CMD, cmd);
+
+
+	port_out8(iobase + CONFIG1, 0); /* power on */
+
+	port_out8(iobase + CMD, 0x10); /* software reset */
+	while (port_in8(iobase + CMD) & 0x10);
+
+	assert((long)(void*)rxbuf <= 0xFFFFFFFF);
+	port_out32(iobase + RBSTART, (long)(void*)rxbuf);
+
+	uint32_t rcr = 0;
+	// rcr |= 1 << 0; /* accept all packets */
+	rcr |= 1 << 1; /* accept packets with our mac */
+	rcr |= 1 << 2; /* accept multicast */
+	rcr |= 1 << 3; /* accept broadcast */
+	rcr |= 1 << 7; /* WARP */
+	rcr |= buflen_shift << 11;
+	rcr |= 7 << 13; /* no rx threshold, copy whole packets */
+	port_out32(iobase + RCR, rcr);
+
+	port_out8(iobase + CMD, 0xC); /* enable RX TX */
+
+	rx_irq_enable(false);
+
+	uint64_t mac = (((uint64_t)port_in32(iobase + MAC + 4) & 0xFFFF) << 32) + port_in32(iobase + MAC);
+	kprintf("rtl8139 mac %012x\n", mac);
+
+	vfs_mount_root_register("/eth", &backend);
+}
+
+void rtl8139_irq(void) {
+	uint16_t status = port_in16(iobase + INTRSTATUS);
+	// TODO don't assume this is an rx irq
+
+	do {
+		if (blocked_on) {
+			accept(blocked_on);
+			blocked_on = blocked_on->postqueue_next;
+		} else {
+			rx_irq_enable(false);
+			break;
+		}
+	} while (!(port_in8(iobase + CMD) & 1)); /* bit 0 - Rx Buffer Empty */
+
+	//kprintf("rxpos %x cbr %x\n", rxpos, port_in16(iobase + CBR));
+	port_out16(iobase + INTRSTATUS, status);
+}
+
+static int try_rx(struct pagedir *pages, void __user *dest, size_t dlen) {
+	uint16_t flags, size, pktsize;
+	/* bit 0 - Rx Buffer Empty */
+	if (port_in8(iobase + CMD) & 1) return -1;
+
+	/* https://github.com/qemu/qemu/blob/04ddcda6a/hw/net/rtl8139.c#L1169 */
+	/* https://www.cs.usfca.edu/~cruse/cs326f04/RTL8139D_DataSheet.pdf page 12
+	 * bits of interest:
+	 *  0 - Receive OK
+	 * 14 - Physical Address Matched */
+	flags = *(uint16_t*)(rxbuf + rxpos);
+	rxpos += 2;
+	/* doesn't include the header, includes a 4 byte crc */
+	size = *(uint16_t*)(rxbuf + rxpos);
+	rxpos += 2;
+	if (size == 0) panic_invalid_state();
+	pktsize = size - 4;
+
+	// kprintf("packet size 0x%x, flags 0x%x, rxpos %x\n", size, flags, rxpos - 4);
+	virt_cpy_to(pages, dest, rxbuf + rxpos, pktsize);
+
+	rxpos += size;
+	rxpos = (rxpos + 3) & ~3;
+	while (rxpos >= rxbuf_baselen) rxpos -= rxbuf_baselen;
+	/* the device adds the 0x10 back, it's supposed to avoid overflow */
+	port_out16(iobase + CAPR, rxpos - 0x10);
+	return pktsize;
+}
+
+static void accept(struct vfs_request *req) {
+	switch (req->type) {
+		long ret;
+		case VFSOP_OPEN:
+			vfsreq_finish_short(req, req->input.len == 0 ? 0 : -1);
+			break;
+		case VFSOP_READ:
+			if (!req->caller) {
+				vfsreq_finish_short(req, -1);
+				break;
+			}
+			ret = try_rx(req->caller->pages, req->output.buf, req->output.len);
+			if (ret < 0) {
+				// TODO this is a pretty common pattern in drivers, try to make it unneeded
+				assert(!req->postqueue_next);
+				struct vfs_request **slot = &blocked_on;
+				while (*slot) slot = &(*slot)->postqueue_next;
+				*slot = req;
+				rx_irq_enable(true);
+			} else {
+				vfsreq_finish_short(req, ret);
+			}
+			break;
+		default:
+			vfsreq_finish_short(req, -1);
+			break;
+	}
+}
-- 
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