path: root/drivers/block/rsxx/dma.c

/*
* Filename: dma.c
*
*
* Authors: Joshua Morris <josh.h.morris@us.ibm.com>
*	Philip Kelleher <pjk1939@linux.vnet.ibm.com>
*
* (C) Copyright 2013 IBM Corporation
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/

#include <linux/slab.h>
#include "rsxx_priv.h"

struct rsxx_dma {
	struct list_head	 list;
	u8			 cmd;
	unsigned int		 laddr;     /* Logical address on the ramsan */
	struct {
		u32		 off;
		u32		 cnt;
	} sub_page;
	dma_addr_t		 dma_addr;
	struct page		 *page;
	unsigned int		 pg_off;    /* Page Offset */
	rsxx_dma_cb		 cb;
	void			 *cb_data;
};

/* This timeout is used to detect a stalled DMA channel */
#define DMA_ACTIVITY_TIMEOUT	msecs_to_jiffies(10000)

struct hw_status {
	u8	status;
	u8	tag;
	__le16	count;
	__le32	_rsvd2;
	__le64	_rsvd3;
} __packed;

enum rsxx_dma_status {
	DMA_SW_ERR    = 0x1,
	DMA_HW_FAULT  = 0x2,
	DMA_CANCELLED = 0x4,
};

struct hw_cmd {
	u8	command;
	u8	tag;
	u8	_rsvd;
	u8	sub_page; /* Bit[0:2]: 512byte offset */
			  /* Bit[4:6]: 512byte count */
	__le32	device_addr;
	__le64	host_addr;
} __packed;

enum rsxx_hw_cmd {
	HW_CMD_BLK_DISCARD	= 0x70,
	HW_CMD_BLK_WRITE	= 0x80,
	HW_CMD_BLK_READ		= 0xC0,
	HW_CMD_BLK_RECON_READ	= 0xE0,
};

enum rsxx_hw_status {
	HW_STATUS_CRC		= 0x01,
	HW_STATUS_HARD_ERR	= 0x02,
	HW_STATUS_SOFT_ERR	= 0x04,
	HW_STATUS_FAULT		= 0x08,
};

#define STATUS_BUFFER_SIZE8     4096
#define COMMAND_BUFFER_SIZE8    4096

static struct kmem_cache *rsxx_dma_pool;

struct dma_tracker {
	int			next_tag;
	struct rsxx_dma	*dma;
};

#define DMA_TRACKER_LIST_SIZE8 (sizeof(struct dma_tracker_list) + \
		(sizeof(struct dma_tracker) * RSXX_MAX_OUTSTANDING_CMDS))

struct dma_tracker_list {
	spinlock_t		lock;
	int			head;
	struct dma_tracker	list[0];
};


/*----------------- Misc Utility Functions -------------------*/
static unsigned int rsxx_addr8_to_laddr(u64 addr8, struct rsxx_cardinfo *card)
{
	unsigned long long tgt_addr8;

	tgt_addr8 = ((addr8 >> card->_stripe.upper_shift) &
		      card->_stripe.upper_mask) |
		    ((addr8) & card->_stripe.lower_mask);
	do_div(tgt_addr8, RSXX_HW_BLK_SIZE);
	return tgt_addr8;
}

static unsigned int rsxx_get_dma_tgt(struct rsxx_cardinfo *card, u64 addr8)
{
	unsigned int tgt;

	tgt = (addr8 >> card->_stripe.target_shift) & card->_stripe.target_mask;

	return tgt;
}

static void rsxx_dma_queue_reset(struct rsxx_cardinfo *card)
{
	/* Reset all DMA Command/Status Queues */
	iowrite32(DMA_QUEUE_RESET, card->regmap + RESET);
}

static unsigned int get_dma_size(struct rsxx_dma *dma)
{
	if (dma->sub_page.cnt)
		return dma->sub_page.cnt << 9;
	else
		return RSXX_HW_BLK_SIZE;
}


/*----------------- DMA Tracker -------------------*/
static void set_tracker_dma(struct dma_tracker_list *trackers,
			    int tag,
			    struct rsxx_dma *dma)
{
	trackers->list[tag].dma = dma;
}

static struct rsxx_dma *get_tracker_dma(struct dma_tracker_list *trackers,
					    int tag)
{
	return trackers->list[tag].dma;
}

static int pop_tracker(struct dma_tracker_list *trackers)
{
	int tag;

	spin_lock(&trackers->lock);
	tag = trackers->head;
	if (tag != -1) {
		trackers->head = trackers->list[tag].next_tag;
		trackers->list[tag].next_tag = -1;
	}
	spin_unlock(&trackers->lock);

	return tag;
}

static void push_tracker(struct dma_tracker_list *trackers, int tag)
{
	spin_lock(&trackers->lock);
	trackers->list[tag].next_tag = trackers->head;
	trackers->head = tag;
	trackers->list[tag].dma = NULL;
	spin_unlock(&trackers->lock);
}


/*----------------- Interrupt Coalescing -------------*/
/*
 * Interrupt Coalescing Register Format:
 * Interrupt Timer (64ns units) [15:0]
 * Interrupt Count [24:16]
 * Reserved [31:25]
*/
#define INTR_COAL_LATENCY_MASK       (0x0000ffff)

#define INTR_COAL_COUNT_SHIFT        16
#define INTR_COAL_COUNT_BITS         9
#define INTR_COAL_COUNT_MASK         (((1 << INTR_COAL_COUNT_BITS) - 1) << \
					INTR_COAL_COUNT_SHIFT)
#define INTR_COAL_LATENCY_UNITS_NS   64


static u32<