diff options
Diffstat (limited to 'drivers/dma/apbh_dma.c')
| -rw-r--r-- | drivers/dma/apbh_dma.c | 691 |
1 files changed, 691 insertions, 0 deletions
diff --git a/drivers/dma/apbh_dma.c b/drivers/dma/apbh_dma.c new file mode 100644 index 000000000..69a10428e --- /dev/null +++ b/drivers/dma/apbh_dma.c @@ -0,0 +1,691 @@ +/* + * 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; +} + +/* + * 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. + */ +int mxs_dma_enable(int channel) +{ + struct mx28_apbh_regs *apbh_regs = + (struct mx28_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. + */ +int mxs_dma_disable(int channel) +{ + struct mxs_dma_chan *pchan; + struct mx28_apbh_regs *apbh_regs = + (struct mx28_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. + */ +int mxs_dma_reset(int channel) +{ + struct mx28_apbh_regs *apbh_regs = + (struct mx28_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; +} + +/* + * Freeze a DMA channel. + * + * This function causes the channel to continuously fail arbitration for bus + * access, which halts all forward progress without losing any state. A call to + * mxs_dma_unfreeze() will cause the channel to continue its current operation + * with no ill effect. + */ +int mxs_dma_freeze(int channel) +{ + struct mx28_apbh_regs *apbh_regs = + (struct mx28_apbh_regs *)MXS_APBH_BASE; + int ret; + + ret = mxs_dma_validate_chan(channel); + if (ret) + return ret; + + writel(1 << (channel + APBH_CHANNEL_CTRL_FREEZE_CHANNEL_OFFSET), + &apbh_regs->hw_apbh_channel_ctrl_set); + + return 0; +} + +/* + * Unfreeze a DMA channel. + * + * This function reverses the effect of mxs_dma_freeze(), enabling the DMA + * channel to continue from where it was frozen. + */ +int mxs_dma_unfreeze(int channel) +{ + struct mx28_apbh_regs *apbh_regs = + (struct mx28_apbh_regs *)MXS_APBH_BASE; + int ret; + + ret = mxs_dma_validate_chan(channel); + if (ret) + return ret; + + writel(1 << (channel + APBH_CHANNEL_CTRL_FREEZE_CHANNEL_OFFSET), + &apbh_regs->hw_apbh_channel_ctrl_clr); + + return 0; +} + +/* + * 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. + */ +int mxs_dma_read_semaphore(int channel) +{ + struct mx28_apbh_regs *apbh_regs = + (struct mx28_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; +} + +/* + * Enable or disable DMA interrupt. + * + * This function enables the given DMA channel to interrupt the CPU. + */ +int mxs_dma_enable_irq(int channel, int enable) +{ + struct mx28_apbh_regs *apbh_regs = + (struct mx28_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; +} + +/* + * Check if a DMA interrupt is pending. + */ +int mxs_dma_irq_is_pending(int channel) +{ + struct mx28_apbh_regs *apbh_regs = + (struct mx28_apbh_regs *)MXS_APBH_BASE; + uint32_t tmp; + int ret; + + ret = mxs_dma_validate_chan(channel); + if (ret) + return ret; + + tmp = readl(&apbh_regs->hw_apbh_ctrl1); + tmp |= readl(&apbh_regs->hw_apbh_ctrl2); + + return (tmp >> channel) & 1; +} + +/* + * 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. + */ +int mxs_dma_ack_irq(int channel) +{ + struct mx28_apbh_regs *apbh_regs = + (struct mx28_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 + */ +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; + + pdesc = memalign(MXS_DMA_ALIGNMENT, sizeof(struct mxs_dma_desc)); + + 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); +} + +/* + * Return the address of the command within a descriptor. + */ +unsigned int mxs_dma_cmd_address(struct mxs_dma_desc *desc) +{ + return desc->address + offsetof(struct mxs_dma_desc, cmd); +} + +/* + * Check if descriptor is on a channel's active list. + * + * This function returns the state of a descriptor's "ready" flag. This flag is + * usually set only if the descriptor appears on a channel's active list. The + * descriptor may or may not have already been processed by the hardware. + * + * The "ready" flag is set when the descriptor is submitted to a channel by a + * call to mxs_dma_append() or mxs_dma_append_list(). The "ready" flag is + * cleared when a processed descriptor is moved off the active list by a call + * to mxs_dma_finish(). The "ready" flag is NOT cleared if the descriptor is + * aborted by a call to mxs_dma_disable(). + */ +int mxs_dma_desc_pending(struct mxs_dma_desc *pdesc) +{ + return pdesc->flags & MXS_DMA_DESC_READY; +} + +/* + * 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; + } + pdesc->flags |= MXS_DMA_DESC_READY; + if (pdesc->flags & MXS_DMA_DESC_FIRST) + pchan->pending_num++; + list_add_tail(&pdesc->node, &pchan->active); + + return ret; +} + +/* + * Retrieve processed DMA descriptors. + * + * This function moves all the descriptors from the DMA channel's "done" list to + * the head of the given list. + */ +int mxs_dma_get_finished(int channel, struct list_head *head) +{ + struct mxs_dma_chan *pchan; + int ret; + + ret = mxs_dma_validate_chan(channel); + if (ret) + return ret; + + if (head == NULL) + return 0; + + pchan = mxs_dma_channels + channel; + + list_splice(&pchan->done, head); + + return 0; +} + +/* + * 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. + */ +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 + */ +int mxs_dma_wait_complete(uint32_t timeout, unsigned int chan) +{ + struct mx28_apbh_regs *apbh_regs = + (struct mx28_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 0; +} + +/* + * 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 + */ +int mxs_dma_init(void) +{ + struct mx28_apbh_regs *apbh_regs = + (struct mx28_apbh_regs *)MXS_APBH_BASE; + struct mxs_dma_chan *pchan; + int ret, channel; + + 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 + + for (channel = 0; channel < MXS_MAX_DMA_CHANNELS; channel++) { + 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); + + goto err; + } + + mxs_dma_reset(channel); + mxs_dma_ack_irq(channel); + } + + return 0; + +err: + while (--channel >= 0) + mxs_dma_release(channel); + return ret; +} |