[ARM] 3444/1: i.MX: Scatter-gather DMA emulation for i.MX/MX1

Patch from Pavel Pisa

This patch contains simplified set of changes to add scatter-gather
emulation capability into MX1 DMA support. The result should
be still usable for next combination of DMA transfers
  Statter-Gather/linear/2D/FIFO to linear/2D/FIFO and
  linear/2D/FIFO to Statter-Gather/2D/FIFO
The patch corrects channel priority allocation to be compatible
with MX1 hardware implementation.
Previous code has not been adapted from its PXA original.

Signed-off-by: Pavel Pisa <pisa@cmp.felk.cvut.cz>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 448 insertions, 63 deletions

diff --git a/arch/arm/mach-imx/dma.c b/arch/arm/mach-imx/dma.c
index 71a59e196166..4ca51dcf13ac 100644
--- a/arch/arm/mach-imx/dma.c
+++ b/arch/arm/mach-imx/dma.c
@@ -7,11 +7,18 @@
  *  it under the terms of the GNU General Public License version 2 as
  *  published by the Free Software Foundation.
  *
- *  03/03/2004 Sascha Hauer <sascha@saschahauer.de>
+ *  2004-03-03 Sascha Hauer <sascha@saschahauer.de>
  *             initial version heavily inspired by
  *             linux/arch/arm/mach-pxa/dma.c
+ *
+ *  2005-04-17 Pavel Pisa <pisa@cmp.felk.cvut.cz>
+ *             Changed to support scatter gather DMA
+ *             by taking Russell's code from RiscPC
+ *
  */
 
+#undef DEBUG
+
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
@@ -22,69 +29,368 @@
 #include <asm/irq.h>
 #include <asm/hardware.h>
 #include <asm/dma.h>
+#include <asm/arch/imx-dma.h>
+
+struct imx_dma_channel imx_dma_channels[IMX_DMA_CHANNELS];
+
+/*
+ * imx_dma_sg_next - prepare next chunk for scatter-gather DMA emulation
+ * @dma_ch: i.MX DMA channel number
+ * @lastcount: number of bytes transferred during last transfer
+ *
+ * Functions prepares DMA controller for next sg data chunk transfer.
+ * The @lastcount argument informs function about number of bytes transferred
+ * during last block. Zero value can be used for @lastcount to setup DMA
+ * for the first chunk.
+ */
+static inline int imx_dma_sg_next(imx_dmach_t dma_ch, unsigned int lastcount)
+{
+        struct imx_dma_channel *imxdma = &imx_dma_channels[dma_ch];
+        unsigned int nextcount;
+        unsigned int nextaddr;
+
+        if (!imxdma->name) {
+                printk(KERN_CRIT "%s: called for  not allocated channel %d\n",
+                       __FUNCTION__, dma_ch);
+                return 0;
+        }
+
+        imxdma->resbytes -= lastcount;
+
+        if (!imxdma->sg) {
+                pr_debug("imxdma%d: no sg data\n", dma_ch);
+                return 0;
+        }
+
+        imxdma->sgbc += lastcount;
+        if ((imxdma->sgbc >= imxdma->sg->length) || !imxdma->resbytes) {
+                if ((imxdma->sgcount <= 1) || !imxdma->resbytes) {
+                        pr_debug("imxdma%d: sg transfer limit reached\n",
+                                 dma_ch);
+                        imxdma->sgcount=0;
+                        imxdma->sg = NULL;
+                        return 0;
+                } else {
+                        imxdma->sgcount--;
+                        imxdma->sg++;
+                        imxdma->sgbc = 0;
+                }
+        }
+        nextcount = imxdma->sg->length - imxdma->sgbc;
+        nextaddr = imxdma->sg->dma_address + imxdma->sgbc;
 
-static struct dma_channel {
-        char *name;
-        void (*irq_handler) (int, void *, struct pt_regs *);
-        void (*err_handler) (int, void *, struct pt_regs *);
-        void *data;
-} dma_channels[11];
+        if(imxdma->resbytes < nextcount)
+                nextcount = imxdma->resbytes;
 
-/* set err_handler to NULL to have the standard info-only error handler */
+        if ((imxdma->dma_mode & DMA_MODE_MASK) == DMA_MODE_READ)
+                DAR(dma_ch) = nextaddr;
+        else
+                SAR(dma_ch) = nextaddr;
+
+        CNTR(dma_ch) = nextcount;
+        pr_debug("imxdma%d: next sg chunk dst 0x%08x, src 0x%08x, size 0x%08x\n",
+                 dma_ch, DAR(dma_ch), SAR(dma_ch), CNTR(dma_ch));
+
+        return nextcount;
+}
+
+/*
+ * imx_dma_setup_sg_base - scatter-gather DMA emulation
+ * @dma_ch: i.MX DMA channel number
+ * @sg: pointer to the scatter-gather list/vector
+ * @sgcount: scatter-gather list hungs count
+ *
+ * Functions sets up i.MX DMA state for emulated scatter-gather transfer
+ * and sets up channel registers to be ready for the first chunk
+ */
+static int
+imx_dma_setup_sg_base(imx_dmach_t dma_ch,
+                      struct scatterlist *sg, unsigned int sgcount)
+{
+        struct imx_dma_channel *imxdma = &imx_dma_channels[dma_ch];
+
+        imxdma->sg = sg;
+        imxdma->sgcount = sgcount;
+        imxdma->sgbc = 0;
+        return imx_dma_sg_next(dma_ch, 0);
+}
+
+/**
+ * imx_dma_setup_single - setup i.MX DMA channel for linear memory to/from device transfer
+ * @dma_ch: i.MX DMA channel number
+ * @dma_address: the DMA/physical memory address of the linear data block
+ *              to transfer
+ * @dma_length: length of the data block in bytes
+ * @dev_addr: physical device port address
+ * @dmamode: DMA transfer mode, %DMA_MODE_READ from the device to the memory
+ *           or %DMA_MODE_WRITE from memory to the device
+ *
+ * The function setups DMA channel source and destination addresses for transfer
+ * specified by provided parameters. The scatter-gather emulation is disabled,
+ * because linear data block
+ * form the physical address range is transfered.
+ * Return value: if incorrect parameters are provided -%EINVAL.
+ *              Zero indicates success.
+ */
 int
-imx_request_dma(char *name, imx_dma_prio prio,
-                void (*irq_handler) (int, void *, struct pt_regs *),
-                void (*err_handler) (int, void *, struct pt_regs *), void *data)
+imx_dma_setup_single(imx_dmach_t dma_ch, dma_addr_t dma_address,
+                     unsigned int dma_length, unsigned int dev_addr,
+                     dmamode_t dmamode)
 {
-        unsigned long flags;
-        int i, found = 0;
+        struct imx_dma_channel *imxdma = &imx_dma_channels[dma_ch];
 
-        /* basic sanity checks */
-        if (!name || !irq_handler)
+        imxdma->sg = NULL;
+        imxdma->sgcount = 0;
+        imxdma->dma_mode = dmamode;
+        imxdma->resbytes = dma_length;
+
+        if (!dma_address) {
+                printk(KERN_ERR "imxdma%d: imx_dma_setup_single null address\n",
+                       dma_ch);
                 return -EINVAL;
+        }
 
-        local_irq_save(flags);
+        if (!dma_length) {
+                printk(KERN_ERR "imxdma%d: imx_dma_setup_single zero length\n",
+                       dma_ch);
+                return -EINVAL;
+        }
 
-        /* try grabbing a DMA channel with the requested priority */
-        for (i = prio; i < prio + (prio == DMA_PRIO_LOW) ? 8 : 4; i++) {
-                if (!dma_channels[i].name) {
-                        found = 1;
-                        break;
-                }
+        if ((dmamode & DMA_MODE_MASK) == DMA_MODE_READ) {
+                pr_debug("imxdma%d: mx_dma_setup_single2dev dma_addressg=0x%08x dma_length=%d dev_addr=0x%08x for read\n",
+                        dma_ch, (unsigned int)dma_address, dma_length,
+                        dev_addr);
+                SAR(dma_ch) = dev_addr;
+                DAR(dma_ch) = (unsigned int)dma_address;
+        } else if ((dmamode & DMA_MODE_MASK) == DMA_MODE_WRITE) {
+                pr_debug("imxdma%d: mx_dma_setup_single2dev dma_addressg=0x%08x dma_length=%d dev_addr=0x%08x for write\n",
+                        dma_ch, (unsigned int)dma_address, dma_length,
+                        dev_addr);
+                SAR(dma_ch) = (unsigned int)dma_address;
+                DAR(dma_ch) = dev_addr;
+        } else {
+                printk(KERN_ERR "imxdma%d: imx_dma_setup_single bad dmamode\n",
+                       dma_ch);
+                return -EINVAL;
         }
 
-        if (!found) {
-                /* requested prio group is full, try hier priorities */
-                for (i = prio - 1; i >= 0; i--) {
-                        if (!dma_channels[i].name) {
-                                found = 1;
-                                break;
-                        }
-                }
+        CNTR(dma_ch) = dma_length;
+
+        return 0;
+}
+
+/**
+ * imx_dma_setup_sg - setup i.MX DMA channel SG list to/from device transfer
+ * @dma_ch: i.MX DMA channel number
+ * @sg: pointer to the scatter-gather list/vector
+ * @sgcount: scatter-gather list hungs count
+ * @dma_length: total length of the transfer request in bytes
+ * @dev_addr: physical device port address
+ * @dmamode: DMA transfer mode, %DMA_MODE_READ from the device to the memory
+ *           or %DMA_MODE_WRITE from memory to the device
+ *
+ * The function setups DMA channel state and registers to be ready for transfer
+ * specified by provided parameters. The scatter-gather emulation is set up
+ * according to the parameters.
+ *
+ * The full preparation of the transfer requires setup of more register
+ * by the caller before imx_dma_enable() can be called.
+ *
+ * %BLR(dma_ch) holds transfer burst length in bytes, 0 means 64 bytes
+ *
+ * %RSSR(dma_ch) has to be set to the DMA request line source %DMA_REQ_xxx
+ *
+ * %CCR(dma_ch) has to specify transfer parameters, the next settings is typical
+ * for linear or simple scatter-gather transfers if %DMA_MODE_READ is specified
+ *
+ * %CCR_DMOD_LINEAR | %CCR_DSIZ_32 | %CCR_SMOD_FIFO | %CCR_SSIZ_x
+ *
+ * The typical setup for %DMA_MODE_WRITE is specified by next options combination
+ *
+ * %CCR_SMOD_LINEAR | %CCR_SSIZ_32 | %CCR_DMOD_FIFO | %CCR_DSIZ_x
+ *
+ * Be carefull there and do not mistakenly mix source and target device
+ * port sizes constants, they are really different:
+ * %CCR_SSIZ_8, %CCR_SSIZ_16, %CCR_SSIZ_32,
+ * %CCR_DSIZ_8, %CCR_DSIZ_16, %CCR_DSIZ_32
+ *
+ * Return value: if incorrect parameters are provided -%EINVAL.
+ * Zero indicates success.
+ */
+int
+imx_dma_setup_sg(imx_dmach_t dma_ch,
+                 struct scatterlist *sg, unsigned int sgcount, unsigned int dma_length,
+                 unsigned int dev_addr, dmamode_t dmamode)
+{
+        int res;
+        struct imx_dma_channel *imxdma = &imx_dma_channels[dma_ch];
+
+        imxdma->sg = NULL;
+        imxdma->sgcount = 0;
+        imxdma->dma_mode = dmamode;
+        imxdma->resbytes = dma_length;
+
+        if (!sg || !sgcount) {
+                printk(KERN_ERR "imxdma%d: imx_dma_setup_sg epty sg list\n",
+                       dma_ch);
+                return -EINVAL;
+        }
+
+        if (!sg->length) {
+                printk(KERN_ERR "imxdma%d: imx_dma_setup_sg zero length\n",
+                       dma_ch);
+                return -EINVAL;
         }
 
-        if (found) {
-                DIMR &= ~(1 << i);
-                dma_channels[i].name = name;
-                dma_channels[i].irq_handler = irq_handler;
-                dma_channels[i].err_handler = err_handler;
-                dma_channels[i].data = data;
+        if ((dmamode & DMA_MODE_MASK) == DMA_MODE_READ) {
+                pr_debug("imxdma%d: mx_dma_setup_sg2dev sg=%p sgcount=%d total length=%d dev_addr=0x%08x for read\n",
+                        dma_ch, sg, sgcount, dma_length, dev_addr);
+                SAR(dma_ch) = dev_addr;
+        } else if ((dmamode & DMA_MODE_MASK) == DMA_MODE_WRITE) {
+                pr_debug("imxdma%d: mx_dma_setup_sg2dev sg=%p sgcount=%d total length=%d dev_addr=0x%08x for write\n",
+                        dma_ch, sg, sgcount, dma_length, dev_addr);
+                DAR(dma_ch) = dev_addr;
         } else {
-                printk(KERN_WARNING "No more available DMA channels for %s\n",
-                       name);
-                i = -ENODEV;
+                printk(KERN_ERR "imxdma%d: imx_dma_setup_sg bad dmamode\n",
+                       dma_ch);
+                return -EINVAL;
+        }
+
+        res = imx_dma_setup_sg_base(dma_ch, sg, sgcount);
+        if (res <= 0) {
+                printk(KERN_ERR "imxdma%d: no sg chunk ready\n", dma_ch);
+                return -EINVAL;
+        }
+
+        return 0;
+}
+
+/**
+ * imx_dma_setup_handlers - setup i.MX DMA channel end and error notification handlers
+ * @dma_ch: i.MX DMA channel number
+ * @irq_handler: the pointer to the function called if the transfer
+ *              ends successfully
+ * @err_handler: the pointer to the function called if the premature
+ *              end caused by error occurs
+ * @data: user specified value to be passed to the handlers
+ */
+int
+imx_dma_setup_handlers(imx_dmach_t dma_ch,
+                       void (*irq_handler) (int, void *, struct pt_regs *),
+                       void (*err_handler) (int, void *, struct pt_regs *),
+                       void *data)
+{
+        struct imx_dma_channel *imxdma = &imx_dma_channels[dma_ch];
+        unsigned long flags;
+
+        if (!imxdma->name) {
+                printk(KERN_CRIT "%s: called for  not allocated channel %d\n",
+                       __FUNCTION__, dma_ch);
+                return -ENODEV;
+        }
+
+        local_irq_save(flags);
+        DISR = (1 << dma_ch);
+        imxdma->irq_handler = irq_handler;
+        imxdma->err_handler = err_handler;
+        imxdma->data = data;
+        local_irq_restore(flags);
+        return 0;
+}
+
+/**
+ * imx_dma_enable - function to start i.MX DMA channel operation
+ * @dma_ch: i.MX DMA channel number
+ *
+ * The channel has to be allocated by driver through imx_dma_request()
+ * or imx_dma_request_by_prio() function.
+ * The transfer parameters has to be set to the channel registers through
+ * call of the imx_dma_setup_single() or imx_dma_setup_sg() function
+ * and registers %BLR(dma_ch), %RSSR(dma_ch) and %CCR(dma_ch) has to
+ * be set prior this function call by the channel user.
+ */
+void imx_dma_enable(imx_dmach_t dma_ch)
+{
+        struct imx_dma_channel *imxdma = &imx_dma_channels[dma_ch];
+        unsigned long flags;
+
+        pr_debug("imxdma%d: imx_dma_enable\n", dma_ch);
+
+        if (!imxdma->name) {
+                printk(KERN_CRIT "%s: called for  not allocated channel %d\n",
+                       __FUNCTION__, dma_ch);
+                return;
+        }
+
+        local_irq_save(flags);
+        DISR = (1 << dma_ch);
+        DIMR &= ~(1 << dma_ch);
+        CCR(dma_ch) |= CCR_CEN;
+        local_irq_restore(flags);
+}
+
+/**
+ * imx_dma_disable - stop, finish i.MX DMA channel operatin
+ * @dma_ch: i.MX DMA channel number
+ */
+void imx_dma_disable(imx_dmach_t dma_ch)
+{
+        unsigned long flags;
+
+        pr_debug("imxdma%d: imx_dma_disable\n", dma_ch);
+
+        local_irq_save(flags);
+        DIMR |= (1 << dma_ch);
+        CCR(dma_ch) &= ~CCR_CEN;
+        DISR = (1 << dma_ch);
+        local_irq_restore(flags);
+}
+
+/**
+ * imx_dma_request - request/allocate specified channel number
+ * @dma_ch: i.MX DMA channel number
+ * @name: the driver/caller own non-%NULL identification
+ */
+int imx_dma_request(imx_dmach_t dma_ch, const char *name)
+{
+        struct imx_dma_channel *imxdma = &imx_dma_channels[dma_ch];
+        unsigned long flags;
+
+        /* basic sanity checks */
+        if (!name)
+                return -EINVAL;
+
+        if (dma_ch >= IMX_DMA_CHANNELS) {
+                printk(KERN_CRIT "%s: called for  non-existed channel %d\n",
+                       __FUNCTION__, dma_ch);
+                return -EINVAL;
         }
 
+        local_irq_save(flags);
+        if (imxdma->name) {
+                local_irq_restore(flags);
+                return -ENODEV;
+        }
+
+        imxdma->name = name;
+        imxdma->irq_handler = NULL;
+        imxdma->err_handler = NULL;
+        imxdma->data = NULL;
+        imxdma->sg = NULL;
         local_irq_restore(flags);
-        return i;
+        return 0;
 }
 
-void
-imx_free_dma(int dma_ch)
+/**
+ * imx_dma_free - release previously acquired channel
+ * @dma_ch: i.MX DMA channel number
+ */
+void imx_dma_free(imx_dmach_t dma_ch)
 {
         unsigned long flags;
+        struct imx_dma_channel *imxdma = &imx_dma_channels[dma_ch];
 
-        if (!dma_channels[dma_ch].name) {
+        if (!imxdma->name) {
                 printk(KERN_CRIT
                        "%s: trying to free channel %d which is already freed\n",
                        __FUNCTION__, dma_ch);
@@ -92,27 +398,84 @@ imx_free_dma(int dma_ch)
         }
 
         local_irq_save(flags);
-        DIMR &= ~(1 << dma_ch);
-        dma_channels[dma_ch].name = NULL;
+        /* Disable interrupts */
+        DIMR |= (1 << dma_ch);
+        CCR(dma_ch) &= ~CCR_CEN;
+        imxdma->name = NULL;
         local_irq_restore(flags);
 }
 
-static irqreturn_t
-dma_err_handler(int irq, void *dev_id, struct pt_regs *regs)
+/**
+ * imx_dma_request_by_prio - find and request some of free channels best suiting requested priority
+ * @dma_ch: i.MX DMA channel number
+ * @name: the driver/caller own non-%NULL identification
+ * @prio: one of the hardware distinguished priority level:
+ *        %DMA_PRIO_HIGH, %DMA_PRIO_MEDIUM, %DMA_PRIO_LOW
+ *
+ * This function tries to find free channel in the specified priority group
+ * if the priority cannot be achieved it tries to look for free channel
+ * in the higher and then even lower priority groups.
+ *
+ * Return value: If there is no free channel to allocate, -%ENODEV is returned.
+ *               Zero value indicates successful channel allocation.
+ */
+int
+imx_dma_request_by_prio(imx_dmach_t * pdma_ch, const char *name,
+                        imx_dma_prio prio)
+{
+        int i;
+        int best;
+
+        switch (prio) {
+        case (DMA_PRIO_HIGH):
+                best = 8;
+                break;
+        case (DMA_PRIO_MEDIUM):
+                best = 4;
+                break;
+        case (DMA_PRIO_LOW):
+        default:
+                best = 0;
+                break;
+        }
+
+        for (i = best; i < IMX_DMA_CHANNELS; i++) {
+                if (!imx_dma_request(i, name)) {
+                        *pdma_ch = i;
+                        return 0;
+                }
+        }
+
+        for (i = best - 1; i >= 0; i--) {
+                if (!imx_dma_request(i, name)) {
+                        *pdma_ch = i;
+                        return 0;
+                }
+        }
+
+        printk(KERN_ERR "%s: no free DMA channel found\n", __FUNCTION__);
+
+        return -ENODEV;
+}
+
+static irqreturn_t dma_err_handler(int irq, void *dev_id, struct pt_regs *regs)
 {
         int i, disr = DISR;
-        struct dma_channel *channel;
+        struct imx_dma_channel *channel;
         unsigned int err_mask = DBTOSR | DRTOSR | DSESR | DBOSR;
 
         DISR = disr;
-        for (i = 0; i < 11; i++) {
-                channel = &dma_channels[i];
+        for (i = 0; i < IMX_DMA_CHANNELS; i++) {
+                channel = &imx_dma_channels[i];
 
-                if ( (err_mask & 1<<i) && channel->name && channel->err_handler) {
+                if ((err_mask & 1 << i) && channel->name
+                    && channel->err_handler) {
                         channel->err_handler(i, channel->data, regs);
                         continue;
                 }
 
+                imx_dma_channels[i].sg = NULL;
+
                 if (DBTOSR & (1 << i)) {
                         printk(KERN_WARNING
                                "Burst timeout on channel %d (%s)\n",
@@ -141,17 +504,27 @@ dma_err_handler(int irq, void *dev_id, struct pt_regs *regs)
         return IRQ_HANDLED;
 }
 
-static irqreturn_t
-dma_irq_handler(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t dma_irq_handler(int irq, void *dev_id, struct pt_regs *regs)
 {
         int i, disr = DISR;
 
+        pr_debug("imxdma: dma_irq_handler called, disr=0x%08x\n",
+                     disr);
+
         DISR = disr;
-        for (i = 0; i < 11; i++) {
+        for (i = 0; i < IMX_DMA_CHANNELS; i++) {
                 if (disr & (1 << i)) {
-                        struct dma_channel *channel = &dma_channels[i];
-                        if (channel->name && channel->irq_handler) {
-                                channel->irq_handler(i, channel->data, regs);
+                        struct imx_dma_channel *channel = &imx_dma_channels[i];
+                        if (channel->name) {
+                                if (imx_dma_sg_next(i, CNTR(i))) {
+                                        CCR(i) &= ~CCR_CEN;
+                                        mb();
+                                        CCR(i) |= CCR_CEN;
+                                } else {
+                                        if (channel->irq_handler)
+                                                channel->irq_handler(i,
+                                                        channel->data, regs);
+                                }
                         } else {
                                 /*
                                  * IRQ for an unregistered DMA channel:
@@ -165,10 +538,10 @@ dma_irq_handler(int irq, void *dev_id, struct pt_regs *regs)
         return IRQ_HANDLED;
 }
 
-static int __init
-imx_dma_init(void)
+static int __init imx_dma_init(void)
 {
         int ret;
+        int i;
 
         /* reset DMA module */
         DCR = DCR_DRST;
@@ -189,15 +562,27 @@ imx_dma_init(void)
         DCR = DCR_DEN;
 
         /* clear all interrupts */
-        DISR = 0x3ff;
+        DISR = (1 << IMX_DMA_CHANNELS) - 1;
 
         /* enable interrupts */
-        DIMR = 0;
+        DIMR = (1 << IMX_DMA_CHANNELS) - 1;
+
+        for (i = 0; i < IMX_DMA_CHANNELS; i++) {
+                imx_dma_channels[i].sg = NULL;
+                imx_dma_channels[i].dma_num = i;
+        }
 
         return ret;
 }
 
 arch_initcall(imx_dma_init);
 
-EXPORT_SYMBOL(imx_request_dma);
-EXPORT_SYMBOL(imx_free_dma);
+EXPORT_SYMBOL(imx_dma_setup_single);
+EXPORT_SYMBOL(imx_dma_setup_sg);
+EXPORT_SYMBOL(imx_dma_setup_handlers);
+EXPORT_SYMBOL(imx_dma_enable);
+EXPORT_SYMBOL(imx_dma_disable);
+EXPORT_SYMBOL(imx_dma_request);
+EXPORT_SYMBOL(imx_dma_free);
+EXPORT_SYMBOL(imx_dma_request_by_prio);
+EXPORT_SYMBOL(imx_dma_channels);