unicore32 core architecture: mm related: consistent device DMA handling

This patch implements consistent device DMA handling of memory management.
DMA device operations are also here.

Signed-off-by: Guan Xuetao <gxt@mprc.pku.edu.cn>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>

1 files changed, 180 insertions, 0 deletions

diff --git a/arch/unicore32/kernel/dma.c b/arch/unicore32/kernel/dma.c
new file mode 100644
index 000000000000..b8dcc2514e9a
--- /dev/null
+++ b/arch/unicore32/kernel/dma.c
@@ -0,0 +1,180 @@
+/*
+ * linux/arch/unicore32/kernel/dma.c
+ *
+ * Code specific to PKUnity SoC and UniCore ISA
+ *
+ *      Maintained by GUAN Xue-tao <gxt@mprc.pku.edu.cn>
+ *      Copyright (C) 2001-2010 Guan Xuetao
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/interrupt.h>
+#include <linux/errno.h>
+
+#include <asm/system.h>
+#include <asm/irq.h>
+#include <mach/hardware.h>
+#include <mach/dma.h>
+
+struct dma_channel {
+        char *name;
+        puv3_dma_prio prio;
+        void (*irq_handler)(int, void *);
+        void (*err_handler)(int, void *);
+        void *data;
+};
+
+static struct dma_channel dma_channels[MAX_DMA_CHANNELS];
+
+int puv3_request_dma(char *name, puv3_dma_prio prio,
+                         void (*irq_handler)(int, void *),
+                         void (*err_handler)(int, void *),
+                         void *data)
+{
+        unsigned long flags;
+        int i, found = 0;
+
+        /* basic sanity checks */
+        if (!name)
+                return -EINVAL;
+
+        local_irq_save(flags);
+
+        do {
+                /* try grabbing a DMA channel with the requested priority */
+                for (i = 0; i < MAX_DMA_CHANNELS; i++) {
+                        if ((dma_channels[i].prio == prio) &&
+                            !dma_channels[i].name) {
+                                found = 1;
+                                break;
+                        }
+                }
+                /* if requested prio group is full, try a hier priority */
+        } while (!found && prio--);
+
+        if (found) {
+                dma_channels[i].name = name;
+                dma_channels[i].irq_handler = irq_handler;
+                dma_channels[i].err_handler = err_handler;
+                dma_channels[i].data = data;
+        } else {
+                printk(KERN_WARNING "No more available DMA channels for %s\n",
+                                name);
+                i = -ENODEV;
+        }
+
+        local_irq_restore(flags);
+        return i;
+}
+EXPORT_SYMBOL(puv3_request_dma);
+
+void puv3_free_dma(int dma_ch)
+{
+        unsigned long flags;
+
+        if (!dma_channels[dma_ch].name) {
+                printk(KERN_CRIT
+                        "%s: trying to free channel %d which is already freed\n",
+                        __func__, dma_ch);
+                return;
+        }
+
+        local_irq_save(flags);
+        dma_channels[dma_ch].name = NULL;
+        dma_channels[dma_ch].err_handler = NULL;
+        local_irq_restore(flags);
+}
+EXPORT_SYMBOL(puv3_free_dma);
+
+static irqreturn_t dma_irq_handler(int irq, void *dev_id)
+{
+        int i, dint = DMAC_ITCSR;
+
+        for (i = 0; i < MAX_DMA_CHANNELS; i++) {
+                if (dint & DMAC_CHANNEL(i)) {
+                        struct dma_channel *channel = &dma_channels[i];
+
+                        /* Clear TC interrupt of channel i */
+                        DMAC_ITCCR = DMAC_CHANNEL(i);
+                        DMAC_ITCCR = 0;
+
+                        if (channel->name && channel->irq_handler) {
+                                channel->irq_handler(i, channel->data);
+                        } else {
+                                /*
+                                 * IRQ for an unregistered DMA channel:
+                                 * let's clear the interrupts and disable it.
+                                 */
+                                printk(KERN_WARNING "spurious IRQ for"
+                                                " DMA channel %d\n", i);
+                        }
+                }
+        }
+        return IRQ_HANDLED;
+}
+
+static irqreturn_t dma_err_handler(int irq, void *dev_id)
+{
+        int i, dint = DMAC_IESR;
+
+        for (i = 0; i < MAX_DMA_CHANNELS; i++) {
+                if (dint & DMAC_CHANNEL(i)) {
+                        struct dma_channel *channel = &dma_channels[i];
+
+                        /* Clear Err interrupt of channel i */
+                        DMAC_IECR = DMAC_CHANNEL(i);
+                        DMAC_IECR = 0;
+
+                        if (channel->name && channel->err_handler) {
+                                channel->err_handler(i, channel->data);
+                        } else {
+                                /*
+                                 * IRQ for an unregistered DMA channel:
+                                 * let's clear the interrupts and disable it.
+                                 */
+                                printk(KERN_WARNING "spurious IRQ for"
+                                                " DMA channel %d\n", i);
+                        }
+                }
+        }
+        return IRQ_HANDLED;
+}
+
+int __init puv3_init_dma(void)
+{
+        int i, ret;
+
+        /* dma channel priorities on v8 processors:
+         * ch 0 - 1  <--> (0) DMA_PRIO_HIGH
+         * ch 2 - 3  <--> (1) DMA_PRIO_MEDIUM
+         * ch 4 - 5  <--> (2) DMA_PRIO_LOW
+         */
+        for (i = 0; i < MAX_DMA_CHANNELS; i++) {
+                puv3_stop_dma(i);
+                dma_channels[i].name = NULL;
+                dma_channels[i].prio = min((i & 0x7) >> 1, DMA_PRIO_LOW);
+        }
+
+        ret = request_irq(IRQ_DMA, dma_irq_handler, 0, "DMA", NULL);
+        if (ret) {
+                printk(KERN_CRIT "Can't register IRQ for DMA\n");
+                return ret;
+        }
+
+        ret = request_irq(IRQ_DMAERR, dma_err_handler, 0, "DMAERR", NULL);
+        if (ret) {
+                printk(KERN_CRIT "Can't register IRQ for DMAERR\n");
+                free_irq(IRQ_DMA, "DMA");
+                return ret;
+        }
+
+        return 0;
+}
+
+postcore_initcall(puv3_init_dma);