/* * 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 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; } #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 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. */ static 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. */ static 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; } /* * 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 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; } /* * 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 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 */ 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 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 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 mx28_apbh_regs *apbh_regs = (struct mx28_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; }