bgmac.c

/*
 * Driver for (BCM4706)? GBit MAC core on BCMA bus.
 *
 * Copyright (C) 2012 Rafał Miłecki <zajec5@gmail.com>
 *
 * Licensed under the GNU/GPL. See COPYING for details.
 */

#include "bgmac.h"

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/etherdevice.h>
#include <linux/mii.h>
#include <linux/interrupt.h>
#include <linux/dma-mapping.h>
#include <bcm47xx_nvram.h>

static const struct bcma_device_id bgmac_bcma_tbl[] = {
	BCMA_CORE(BCMA_MANUF_BCM, BCMA_CORE_4706_MAC_GBIT, BCMA_ANY_REV, BCMA_ANY_CLASS),
	BCMA_CORE(BCMA_MANUF_BCM, BCMA_CORE_MAC_GBIT, BCMA_ANY_REV, BCMA_ANY_CLASS),
	BCMA_CORETABLE_END
};
MODULE_DEVICE_TABLE(bcma, bgmac_bcma_tbl);

static bool bgmac_wait_value(struct bcma_device *core, u16 reg, u32 mask,
			     u32 value, int timeout)
{
	u32 val;
	int i;

	for (i = 0; i < timeout / 10; i++) {
		val = bcma_read32(core, reg);
		if ((val & mask) == value)
			return true;
		udelay(10);
	}
	pr_err("Timeout waiting for reg 0x%X\n", reg);
	return false;
}

/**************************************************
 * DMA
 **************************************************/

static void bgmac_dma_tx_reset(struct bgmac *bgmac, struct bgmac_dma_ring *ring)
{
	u32 val;
	int i;

	if (!ring->mmio_base)
		return;

	/* Suspend DMA TX ring first.
	 * bgmac_wait_value doesn't support waiting for any of few values, so
	 * implement whole loop here.
	 */
	bgmac_write(bgmac, ring->mmio_base + BGMAC_DMA_TX_CTL,
		    BGMAC_DMA_TX_SUSPEND);
	for (i = 0; i < 10000 / 10; i++) {
		val = bgmac_read(bgmac, ring->mmio_base + BGMAC_DMA_TX_STATUS);
		val &= BGMAC_DMA_TX_STAT;
		if (val == BGMAC_DMA_TX_STAT_DISABLED ||
		    val == BGMAC_DMA_TX_STAT_IDLEWAIT ||
		    val == BGMAC_DMA_TX_STAT_STOPPED) {
			i = 0;
			break;
		}
		udelay(10);
	}
	if (i)
		bgmac_err(bgmac, "Timeout suspending DMA TX ring 0x%X (BGMAC_DMA_TX_STAT: 0x%08X)\n",
			  ring->mmio_base, val);

	/* Remove SUSPEND bit */
	bgmac_write(bgmac, ring->mmio_base + BGMAC_DMA_TX_CTL, 0);
	if (!bgmac_wait_value(bgmac->core,
			      ring->mmio_base + BGMAC_DMA_TX_STATUS,
			      BGMAC_DMA_TX_STAT, BGMAC_DMA_TX_STAT_DISABLED,
			      10000)) {
		bgmac_warn(bgmac, "DMA TX ring 0x%X wasn't disabled on time, waiting additional 300us\n",
			   ring->mmio_base);
		udelay(300);
		val = bgmac_read(bgmac, ring->mmio_base + BGMAC_DMA_TX_STATUS);
		if ((val & BGMAC_DMA_TX_STAT) != BGMAC_DMA_TX_STAT_DISABLED)
			bgmac_err(bgmac, "Reset of DMA TX ring 0x%X failed\n",
				  ring->mmio_base);
	}
}

static void bgmac_dma_tx_enable(struct bgmac *bgmac,
				struct bgmac_dma_ring *ring)
{
	u32 ctl;

	ctl = bgmac_read(bgmac, ring->mmio_base + BGMAC_DMA_TX_CTL);
	ctl |= BGMAC_DMA_TX_ENABLE;
	ctl |= BGMAC_DMA_TX_PARITY_DISABLE;
	bgmac_write(bgmac, ring->mmio_base + BGMAC_DMA_TX_CTL, ctl);
}

static netdev_tx_t bgmac_dma_tx_add(struct bgmac *bgmac,
				    struct bgmac_dma_ring *ring,
				    struct sk_buff *skb)
{
	struct device *dma_dev = bgmac->core->dma_dev;
	struct net_device *net_dev = bgmac->net_dev;
	struct bgmac_dma_desc *dma_desc;
	struct bgmac_slot_info *slot;
	u32 ctl0, ctl1;
	int free_slots;

	if (skb->len > BGMAC_DESC_CTL1_LEN) {
		bgmac_err(bgmac, "Too long skb (%d)\n", skb->len);
		goto err_stop_drop;
	}

	if (ring->start <= ring->end)
		free_slots = ring->start - ring->end + BGMAC_TX_RING_SLOTS;
	else
		free_slots = ring->start - ring->end;
	if (free_slots == 1) {
		bgmac_err(bgmac, "TX ring is full, queue should be stopped!\n");
		netif_stop_queue(net_dev);
		return NETDEV_TX_BUSY;
	}

	slot = &ring->slots[ring->end];
	slot->skb = skb;
	slot->dma_addr = dma_map_single(dma_dev, skb->data, skb->len,
					DMA_TO_DEVICE);
	if (dma_mapping_error(dma_dev, slot->dma_addr)) {
		bgmac_err(bgmac, "Mapping error of skb on ring 0x%X\n",
			  ring->mmio_base);
		goto err_stop_drop;
	}

	ctl0 = BGMAC_DESC_CTL0_IOC | BGMAC_DESC_CTL0_SOF | BGMAC_DESC_CTL0_EOF;
	if (ring->end == ring->num_slots - 1)
		ctl0 |= BGMAC_DESC_CTL0_EOT;
	ctl1 = skb->len & BGMAC_DESC_CTL1_LEN;

	dma_desc = ring->cpu_base;
	dma_desc += ring->end;
	dma_desc->addr_low = cpu_to_le32(lower_32_bits(slot->dma_addr));
	dma_desc->addr_high = cpu_to_le32(upper_32_bits(slot->dma_addr));
	dma_desc->ctl0 = cpu_to_le32(ctl0);
	dma_desc->ctl1 = cpu_to_le32(ctl1);

	wmb();

	/* Increase ring->end to point empty slot. We tell hardware the first
	 * slot it should *not* read.
	 */
	if (++ring->end >= BGMAC_TX_RING_SLOTS)
		ring->end = 0;
	bgmac_write(bgmac, ring->mmio_base + BGMAC_DMA_TX_INDEX,
		    ring->end * sizeof(struct bgmac_dma_desc));

	/* Always keep one slot free to allow detecting bugged calls. */
	if (--free_slots == 1)
		netif_stop_queue(net_dev);

	return NETDEV_TX_OK;

err_stop_drop:
	netif_stop_queue(net_dev);
	dev_kfree_skb(skb);
	return NETDEV_TX_OK;
}

/* Free transmitted packets */
static void bgmac_dma_tx_free(struct bgmac *bgmac, struct bgmac_dma_ring *ring)
{
	struct device *dma_dev = bgmac->core->dma_dev;
	int empty_slot;
	bool freed = false;

	/* The last slot that hardware didn't consume yet */
	empty_slot = bgmac_read(bgmac, ring->mmio_base + BGMAC_DMA_TX_STATUS);
	empty_slot &= BGMAC_DMA_TX_STATDPTR;
	empty_slot /= sizeof(struct bgmac_dma_desc);

	while (ring->start != empty_slot) {
		struct bgmac_slot_info *slot = &ring->slots[ring->start];

		if (slot->skb) {
			/* Unmap no longer used buffer */
			dma_unmap_single(dma_dev, slot->dma_addr,
					 slot->skb->len, DMA_TO_DEVICE);
			slot->dma_addr = 0;

			/* Free memory! :) */
			dev_kfree_skb(slot->skb);
			slot->skb = NULL;
		} else {
			bgmac_err(bgmac, "Hardware reported transmission for empty TX ring slot %d! End of ring: %d\n",
				  ring->start, ring->end);
		}