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/*
* Freescale i.MX28 APBH DMA driver
*
* Copyright (C) 2011 Marek Vasut <marek.vasut@gmail.com>
* on behalf of DENX Software Engineering GmbH
*
* Based on code from LTIB:
* Copyright (C) 2010 Freescale Semiconductor, Inc. All Rights Reserved.
*
* 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.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include <linux/list.h>
#include <common.h>
#include <malloc.h>
#include <asm/errno.h>
#include <asm/io.h>
#include <asm/arch/clock.h>
#include <asm/arch/imx-regs.h>
#include <asm/arch/sys_proto.h>
#include <asm/arch/dma.h>
static struct mxs_dma_chan mxs_dma_channels[MXS_MAX_DMA_CHANNELS];
/*
* Test is the DMA channel is valid channel
*/
int mxs_dma_validate_chan(int channel)
{
struct mxs_dma_chan *pchan;
if ((channel < 0) || (channel >= MXS_MAX_DMA_CHANNELS))
return -EINVAL;
pchan = mxs_dma_channels + channel;
if (!(pchan->flags & MXS_DMA_FLAGS_ALLOCATED))
return -EINVAL;
return 0;
}
/*
* Return the address of the command within a descriptor.
*/
static unsigned int mxs_dma_cmd_address(struct mxs_dma_desc *desc)
{
return desc->address + offsetof(struct mxs_dma_desc, cmd);
}
/*
* Read a DMA channel's hardware semaphore.
*
* As used by the MXS platform's DMA software, the DMA channel's hardware
* semaphore reflects the number of DMA commands the hardware will process, but
* has not yet finished. This is a volatile value read directly from hardware,
* so it must be be viewed as immediately stale.
*
* If the channel is not marked busy, or has finished processing all its
* commands, this value should be zero.
*
* See mxs_dma_append() for details on how DMA command blocks must be configured
* to maintain the expected behavior of the semaphore's value.
*/
static int mxs_dma_read_semaphore(int channel)
{
struct mxs_apbh_regs *apbh_regs =
(struct mxs_apbh_regs *)MXS_APBH_BASE;
uint32_t tmp;
int ret;
ret = mxs_dma_validate_chan(channel);
if (ret)
return ret;
tmp = readl(&apbh_regs->ch[channel].hw_apbh_ch_sema);
tmp &= APBH_CHn_SEMA_PHORE_MASK;
tmp >>= APBH_CHn_SEMA_PHORE_OFFSET;
return tmp;
}
#ifndef CONFIG_SYS_DCACHE_OFF
void mxs_dma_flush_desc(struct mxs_dma_desc *desc)
{
uint32_t addr;
uint32_t size;
addr = (uint32_t)desc;
size = roundup(sizeof(struct mxs_dma_desc), MXS_DMA_ALIGNMENT);
flush_dcache_range(addr, addr + size);
}
#else
inline void mxs_dma_flush_desc(struct mxs_dma_desc *desc) {}
#endif
/*
* Enable a DMA channel.
*
* If the given channel has any DMA descriptors on its active list, this
* function causes the DMA hardware to begin processing them.
*
* This function marks the DMA channel as "busy," whether or not there are any
* descriptors to process.
*/
static int mxs_dma_enable(int channel)
{
struct mxs_apbh_regs *apbh_regs =
(struct mxs_apbh_regs *)MXS_APBH_BASE;
unsigned int sem;
struct mxs_dma_chan *pchan;
struct mxs_dma_desc *pdesc;
int ret;
ret = mxs_dma_validate_chan(channel);
if (ret)
return ret;
pchan = mxs_dma_channels + channel;
if (pchan->pending_num == 0) {
pchan->flags |= MXS_DMA_FLAGS_BUSY;
return 0;
}
pdesc = list_first_entry(&pchan->active, struct mxs_dma_desc, node);
if (pdesc == NULL)
return -EFAULT;
if (pchan->flags & MXS_DMA_FLAGS_BUSY) {
if (!(pdesc->cmd.data & MXS_DMA_DESC_CHAIN))
return 0;
sem = mxs_dma_read_semaphore(channel);
if (sem == 0)
return 0;
if (sem == 1) {
pdesc = list_entry(pdesc->node.next,
struct mxs_dma_desc, node);
writel(mxs_dma_cmd_address(pdesc),
&apbh_regs->ch[channel].hw_apbh_ch_nxtcmdar);
}
writel(pchan->pending_num,
&apbh_regs->ch[channel].hw_apbh_ch_sema);
pchan->active_num += pchan->pending_num;
pchan->pending_num = 0;
} else {
pchan->active_num += pchan->pending_num;
pchan->pending_num = 0;
writel(mxs_dma_cmd_address(pdesc),
&apbh_regs->ch[channel].hw_apbh_ch_nxtcmdar);
writel(pchan->active_num,
&apbh_regs->ch[channel].hw_apbh_ch_sema);
writel(1 << (channel + APBH_CTRL0_CLKGATE_CHANNEL_OFFSET),
&apbh_regs->hw_apbh_ctrl0_clr);
}
pchan->flags |= MXS_DMA_FLAGS_BUSY;
return 0;
}
/*
* Disable a DMA channel.
*
* This function shuts down a DMA channel and marks it as "not busy." Any
* descriptors on the active list are immediately moved to the head of the
* "done" list, whether or not they have actually been processed by the
* hardware. The "ready" flags of these descriptors are NOT cleared, so they
* still appear to be active.
*
* This function immediately shuts down a DMA channel's hardware, aborting any
* I/O that may be in progress, potentially leaving I/O hardware in an undefined
* state. It is unwise to call this function if there is ANY chance the hardware
* is still processing a command.
*/
static int mxs_dma_disable(int channel)
{
struct mxs_dma_chan *pchan;
struct mxs_apbh_regs *apbh_regs =
(struct mxs_apbh_regs *)MXS_APBH_BASE;
int ret;
ret = mxs_dma_validate_chan(channel);
if (ret)
return ret;
pchan = mxs_dma_channels + channel;
if (!(pchan->flags & MXS_DMA_FLAGS_BUSY))
return -EINVAL;
writel(1 << (channel + APBH_CTRL0_CLKGATE_CHANNEL_OFFSET),
&apbh_regs->hw_apbh_ctrl0_set);
pchan->flags &= ~MXS_DMA_FLAGS_BUSY;
pchan->active_num = 0;
pchan->pending_num = 0;
list_splice_init(&pchan->active, &pchan->done);
return 0;
}
/*
* Resets the DMA channel hardware.
*/
static int mxs_dma_reset(int channel)
{
struct mxs_apbh_regs *apbh_regs =
(struct mxs_apbh_regs *)MXS_APBH_BASE;
int ret;
ret = mxs_dma_validate_chan(channel);
if (ret)
return ret;
writel(1 << (channel + APBH_CHANNEL_CTRL_RESET_CHANNEL_OFFSET),
&apbh_regs->hw_apbh_channel_ctrl_set);
return 0;
}
/*
* Enable or disable DMA interrupt.
*
* This function enables the given DMA channel to interrupt the CPU.
*/
static int mxs_dma_enable_irq(int channel, int enable)
{
struct mxs_apbh_regs *apbh_regs =
(struct mxs_apbh_regs *)MXS_APBH_BASE;
int ret;
ret = mxs_dma_validate_chan(channel);
if (ret)
return ret;
if (enable)
writel(1 << (channel + APBH_CTRL1_CH_CMDCMPLT_IRQ_EN_OFFSET),
&apbh_regs->hw_apbh_ctrl1_set);
else
writel(1 << (channel + APBH_CTRL1_CH_CMDCMPLT_IRQ_EN_OFFSET),
&apbh_regs->hw_apbh_ctrl1_clr);
return 0;
}
/*
* Clear DMA interrupt.
*
* The software that is using the DMA channel must register to receive its
* interrupts and, when they arrive, must call this function to clear them.
*/
static int mxs_dma_ack_irq(int channel)
{
struct mxs_apbh_regs *apbh_regs =
(struct mxs_apbh_regs *)MXS_APBH_BASE;
int ret;
ret = mxs_dma_validate_chan(channel);
if (ret)
return ret;
writel(1 << channel, &apbh_regs->hw_apbh_ctrl1_clr);
writel(1 << channel, &apbh_regs->hw_apbh_ctrl2_clr);
return 0;
}
/*
* Request to reserve a DMA channel
*/
static int mxs_dma_request(int channel)
{
struct mxs_dma_chan *pchan;
if ((channel < 0) || (channel >= MXS_MAX_DMA_CHANNELS))
return -EINVAL;
pchan = mxs_dma_channels + channel;
if ((pchan->flags & MXS_DMA_FLAGS_VALID) != MXS_DMA_FLAGS_VALID)
return -ENODEV;
if (pchan->flags & MXS_DMA_FLAGS_ALLOCATED)
return -EBUSY;
pchan->flags |= MXS_DMA_FLAGS_ALLOCATED;
pchan->active_num = 0;
pchan->pending_num = 0;
INIT_LIST_HEAD(&pchan->active);
INIT_LIST_HEAD(&pchan->done);
return 0;
}
/*
* Release a DMA channel.
*
* This function releases a DMA channel from its current owner.
*
* The channel will NOT be released if it's marked "busy" (see
* mxs_dma_enable()).
*/
int mxs_dma_release(int channel)
{
struct mxs_dma_chan *pchan;
int ret;
ret = mxs_dma_validate_chan(channel);
if (ret)
return ret;
pchan = mxs_dma_channels + channel;
if (pchan->flags & MXS_DMA_FLAGS_BUSY)
return -EBUSY;
pchan->dev = 0;
pchan->active_num = 0;
pchan->pending_num = 0;
pchan->flags &= ~MXS_DMA_FLAGS_ALLOCATED;
return 0;
}
/*
* Allocate DMA descriptor
*/
struct mxs_dma_desc *mxs_dma_desc_alloc(void)
{
struct mxs_dma_desc *pdesc;
uint32_t size;
size = roundup(sizeof(struct mxs_dma_desc), MXS_DMA_ALIGNMENT);
pdesc = memalign(MXS_DMA_ALIGNMENT, size);
if (pdesc == NULL)
return NULL;
memset(pdesc, 0, sizeof(*pdesc));
pdesc->address = (dma_addr_t)pdesc;
return pdesc;
};
/*
* Free DMA descriptor
*/
void mxs_dma_desc_free(struct mxs_dma_desc *pdesc)
{
if (pdesc == NULL)
return;
free(pdesc);
}
/*
* Add a DMA descriptor to a channel.
*
* If the descriptor list for this channel is not empty, this function sets the
* CHAIN bit and the NEXTCMD_ADDR fields in the last descriptor's DMA command so
* it will chain to the new descriptor's command.
*
* Then, this function marks the new descriptor as "ready," adds it to the end
* of the active descriptor list, and increments the count of pending
* descriptors.
*
* The MXS platform DMA software imposes some rules on DMA commands to maintain
* important invariants. These rules are NOT checked, but they must be carefully
* applied by software that uses MXS DMA channels.
*
* Invariant:
* The DMA channel's hardware semaphore must reflect the number of DMA
* commands the hardware will process, but has not yet finished.
*
* Explanation:
* A DMA channel begins processing commands when its hardware semaphore is
* written with a value greater than zero, and it stops processing commands
* when the semaphore returns to zero.
*
* When a channel finishes a DMA command, it will decrement its semaphore if
* the DECREMENT_SEMAPHORE bit is set in that command's flags bits.
*
* In principle, it's not necessary for the DECREMENT_SEMAPHORE to be set,
* unless it suits the purposes of the software. For example, one could
* construct a series of five DMA commands, with the DECREMENT_SEMAPHORE
* bit set only in the last one. Then, setting the DMA channel's hardware
* semaphore to one would cause the entire series of five commands to be
* processed. However, this example would violate the invariant given above.
*
* Rule:
* ALL DMA commands MUST have the DECREMENT_SEMAPHORE bit set so that the DMA
* channel's hardware semaphore will be decremented EVERY time a command is
* processed.
*/
int mxs_dma_desc_append(int channel, struct mxs_dma_desc *pdesc)
{
struct mxs_dma_chan *pchan;
struct mxs_dma_desc *last;
int ret;
ret = mxs_dma_validate_chan(channel);
if (ret)
return ret;
pchan = mxs_dma_channels + channel;
pdesc->cmd.next = mxs_dma_cmd_address(pdesc);
pdesc->flags |= MXS_DMA_DESC_FIRST | MXS_DMA_DESC_LAST;
if (!list_empty(&pchan->active)) {
last = list_entry(pchan->active.prev, struct mxs_dma_desc,
node);
pdesc->flags &= ~MXS_DMA_DESC_FIRST;
last->flags &= ~MXS_DMA_DESC_LAST;
last->cmd.next = mxs_dma_cmd_address(pdesc);
last->cmd.data |= MXS_DMA_DESC_CHAIN;
mxs_dma_flush_desc(last);
}
pdesc->flags |= MXS_DMA_DESC_READY;
if (pdesc->flags & MXS_DMA_DESC_FIRST)
pchan->pending_num++;
list_add_tail(&pdesc->node, &pchan->active);
mxs_dma_flush_desc(pdesc);
return ret;
}
/*
* Clean up processed DMA descriptors.
*
* This function removes processed DMA descriptors from the "active" list. Pass
* in a non-NULL list head to get the descriptors moved to your list. Pass NULL
* to get the descriptors moved to the channel's "done" list. Descriptors on
* the "done" list can be retrieved with mxs_dma_get_finished().
*
* This function marks the DMA channel as "not busy" if no unprocessed
* descriptors remain on the "active" list.
*/
static int mxs_dma_finish(int channel, struct list_head *head)
{
int sem;
struct mxs_dma_chan *pchan;
struct list_head *p, *q;
struct mxs_dma_desc *pdesc;
int ret;
ret = mxs_dma_validate_chan(channel);
if (ret)
return ret;
pchan = mxs_dma_channels + channel;
sem = mxs_dma_read_semaphore(channel);
if (sem < 0)
return sem;
if (sem == pchan->active_num)
return 0;
list_for_each_safe(p, q, &pchan->active) {
if ((pchan->active_num) <= sem)
break;
pdesc = list_entry(p, struct mxs_dma_desc, node);
pdesc->flags &= ~MXS_DMA_DESC_READY;
if (head)
list_move_tail(p, head);
else
list_move_tail(p, &pchan->done);
if (pdesc->flags & MXS_DMA_DESC_LAST)
pchan->active_num--;
}
if (sem == 0)
pchan->flags &= ~MXS_DMA_FLAGS_BUSY;
return 0;
}
/*
* Wait for DMA channel to complete
*/
static int mxs_dma_wait_complete(uint32_t timeout, unsigned int chan)
{
struct mxs_apbh_regs *apbh_regs =
(struct mxs_apbh_regs *)MXS_APBH_BASE;
int ret;
ret = mxs_dma_validate_chan(chan);
if (ret)
return ret;
if (mx28_wait_mask_set(&apbh_regs->hw_apbh_ctrl1_reg,
1 << chan, timeout)) {
ret = -ETIMEDOUT;
mxs_dma_reset(chan);
}
return ret;
}
/*
* Execute the DMA channel
*/
int mxs_dma_go(int chan)
{
uint32_t timeout = 10000;
int ret;
LIST_HEAD(tmp_desc_list);
mxs_dma_enable_irq(chan, 1);
mxs_dma_enable(chan);
/* Wait for DMA to finish. */
ret = mxs_dma_wait_complete(timeout, chan);
/* Clear out the descriptors we just ran. */
mxs_dma_finish(chan, &tmp_desc_list);
/* Shut the DMA channel down. */
mxs_dma_ack_irq(chan);
mxs_dma_reset(chan);
mxs_dma_enable_irq(chan, 0);
mxs_dma_disable(chan);
return ret;
}
/*
* Initialize the DMA hardware
*/
void mxs_dma_init(void)
{
struct mxs_apbh_regs *apbh_regs =
(struct mxs_apbh_regs *)MXS_APBH_BASE;
mx28_reset_block(&apbh_regs->hw_apbh_ctrl0_reg);
#ifdef CONFIG_APBH_DMA_BURST8
writel(APBH_CTRL0_AHB_BURST8_EN,
&apbh_regs->hw_apbh_ctrl0_set);
#else
writel(APBH_CTRL0_AHB_BURST8_EN,
&apbh_regs->hw_apbh_ctrl0_clr);
#endif
#ifdef CONFIG_APBH_DMA_BURST
writel(APBH_CTRL0_APB_BURST_EN,
&apbh_regs->hw_apbh_ctrl0_set);
#else
writel(APBH_CTRL0_APB_BURST_EN,
&apbh_regs->hw_apbh_ctrl0_clr);
#endif
}
int mxs_dma_init_channel(int channel)
{
struct mxs_dma_chan *pchan;
int ret;
pchan = mxs_dma_channels + channel;
pchan->flags = MXS_DMA_FLAGS_VALID;
ret = mxs_dma_request(channel);
if (ret) {
printf("MXS DMA: Can't acquire DMA channel %i\n",
channel);
return ret;
}
mxs_dma_reset(channel);
mxs_dma_ack_irq(channel);
return 0;
}