spi/rspi: add dmaengine support

This patch adds dmaengine supporting using sh_dma driver. The module
receives data by DMAC, it also needs TX DMAC to generate SPI's clocks.

Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

2 files changed, 345 insertions, 6 deletions

diff --git a/drivers/spi/spi-rspi.c b/drivers/spi/spi-rspi.c
index 354f170eab95..4894bde4bbff 100644
--- a/drivers/spi/spi-rspi.c
+++ b/drivers/spi/spi-rspi.c
@@ -31,7 +31,11 @@
 #include <linux/platform_device.h>
 #include <linux/io.h>
 #include <linux/clk.h>
+#include <linux/dmaengine.h>
+#include <linux/dma-mapping.h>
+#include <linux/sh_dma.h>
 #include <linux/spi/spi.h>
+#include <linux/spi/rspi.h>
 
 #define RSPI_SPCR               0x00
 #define RSPI_SSLP               0x01
@@ -141,6 +145,16 @@ struct rspi_data {
         spinlock_t lock;
         struct clk *clk;
         unsigned char spsr;
+
+        /* for dmaengine */
+        struct sh_dmae_slave dma_tx;
+        struct sh_dmae_slave dma_rx;
+        struct dma_chan *chan_tx;
+        struct dma_chan *chan_rx;
+        int irq;
+
+        unsigned dma_width_16bit:1;
+        unsigned dma_callbacked:1;
 };
 
 static void rspi_write8(struct rspi_data *rspi, u8 data, u16 offset)
@@ -265,11 +279,125 @@ static int rspi_send_pio(struct rspi_data *rspi, struct spi_message *mesg,
         return 0;
 }
 
-static int rspi_receive_pio(struct rspi_data *rspi, struct spi_message *mesg,
-                            struct spi_transfer *t)
+static void rspi_dma_complete(void *arg)
+{
+        struct rspi_data *rspi = arg;
+
+        rspi->dma_callbacked = 1;
+        wake_up_interruptible(&rspi->wait);
+}
+
+static int rspi_dma_map_sg(struct scatterlist *sg, void *buf, unsigned len,
+                           struct dma_chan *chan,
+                           enum dma_transfer_direction dir)
+{
+        sg_init_table(sg, 1);
+        sg_set_buf(sg, buf, len);
+        sg_dma_len(sg) = len;
+        return dma_map_sg(chan->device->dev, sg, 1, dir);
+}
+
+static void rspi_dma_unmap_sg(struct scatterlist *sg, struct dma_chan *chan,
+                              enum dma_transfer_direction dir)
+{
+        dma_unmap_sg(chan->device->dev, sg, 1, dir);
+}
+
+static void rspi_memory_to_8bit(void *buf, const void *data, unsigned len)
+{
+        u16 *dst = buf;
+        const u8 *src = data;
+
+        while (len) {
+                *dst++ = (u16)(*src++);
+                len--;
+        }
+}
+
+static void rspi_memory_from_8bit(void *buf, const void *data, unsigned len)
+{
+        u8 *dst = buf;
+        const u16 *src = data;
+
+        while (len) {
+                *dst++ = (u8)*src++;
+                len--;
+        }
+}
+
+static int rspi_send_dma(struct rspi_data *rspi, struct spi_transfer *t)
+{
+        struct scatterlist sg;
+        void *buf = NULL;
+        struct dma_async_tx_descriptor *desc;
+        unsigned len;
+        int ret = 0;
+
+        if (rspi->dma_width_16bit) {
+                /*
+                 * If DMAC bus width is 16-bit, the driver allocates a dummy
+                 * buffer. And, the driver converts original data into the
+                 * DMAC data as the following format:
+                 *  original data: 1st byte, 2nd byte ...
+                 *  DMAC data:     1st byte, dummy, 2nd byte, dummy ...
+                 */
+                len = t->len * 2;
+                buf = kmalloc(len, GFP_KERNEL);
+                if (!buf)
+                        return -ENOMEM;
+                rspi_memory_to_8bit(buf, t->tx_buf, t->len);
+        } else {
+                len = t->len;
+                buf = (void *)t->tx_buf;
+        }
+
+        if (!rspi_dma_map_sg(&sg, buf, len, rspi->chan_tx, DMA_TO_DEVICE)) {
+                ret = -EFAULT;
+                goto end_nomap;
+        }
+        desc = dmaengine_prep_slave_sg(rspi->chan_tx, &sg, 1, DMA_TO_DEVICE,
+                                       DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+        if (!desc) {
+                ret = -EIO;
+                goto end;
+        }
+
+        /*
+         * DMAC needs SPTIE, but if SPTIE is set, this IRQ routine will be
+         * called. So, this driver disables the IRQ while DMA transfer.
+         */
+        disable_irq(rspi->irq);
+
+        rspi_write8(rspi, rspi_read8(rspi, RSPI_SPCR) | SPCR_TXMD, RSPI_SPCR);
+        rspi_enable_irq(rspi, SPCR_SPTIE);
+        rspi->dma_callbacked = 0;
+
+        desc->callback = rspi_dma_complete;
+        desc->callback_param = rspi;
+        dmaengine_submit(desc);
+        dma_async_issue_pending(rspi->chan_tx);
+
+        ret = wait_event_interruptible_timeout(rspi->wait,
+                                               rspi->dma_callbacked, HZ);
+        if (ret > 0 && rspi->dma_callbacked)
+                ret = 0;
+        else if (!ret)
+                ret = -ETIMEDOUT;
+        rspi_disable_irq(rspi, SPCR_SPTIE);
+
+        enable_irq(rspi->irq);
+
+end:
+        rspi_dma_unmap_sg(&sg, rspi->chan_tx, DMA_TO_DEVICE);
+end_nomap:
+        if (rspi->dma_width_16bit)
+                kfree(buf);
+
+        return ret;
+}
+
+static void rspi_receive_init(struct rspi_data *rspi)
 {
-        int remain = t->len;
-        u8 *data;
         unsigned char spsr;
 
         spsr = rspi_read8(rspi, RSPI_SPSR);
@@ -278,6 +406,15 @@ static int rspi_receive_pio(struct rspi_data *rspi, struct spi_message *mesg,
         if (spsr & SPSR_OVRF)
                 rspi_write8(rspi, rspi_read8(rspi, RSPI_SPSR) & ~SPSR_OVRF,
                             RSPI_SPCR);
+}
+
+static int rspi_receive_pio(struct rspi_data *rspi, struct spi_message *mesg,
+                            struct spi_transfer *t)
+{
+        int remain = t->len;
+        u8 *data;
+
+        rspi_receive_init(rspi);
 
         data = (u8 *)t->rx_buf;
         while (remain > 0) {
@@ -307,6 +444,120 @@ static int rspi_receive_pio(struct rspi_data *rspi, struct spi_message *mesg,
         return 0;
 }
 
+static int rspi_receive_dma(struct rspi_data *rspi, struct spi_transfer *t)
+{
+        struct scatterlist sg, sg_dummy;
+        void *dummy = NULL, *rx_buf = NULL;
+        struct dma_async_tx_descriptor *desc, *desc_dummy;
+        unsigned len;
+        int ret = 0;
+
+        if (rspi->dma_width_16bit) {
+                /*
+                 * If DMAC bus width is 16-bit, the driver allocates a dummy
+                 * buffer. And, finally the driver converts the DMAC data into
+                 * actual data as the following format:
+                 *  DMAC data:   1st byte, dummy, 2nd byte, dummy ...
+                 *  actual data: 1st byte, 2nd byte ...
+                 */
+                len = t->len * 2;
+                rx_buf = kmalloc(len, GFP_KERNEL);
+                if (!rx_buf)
+                        return -ENOMEM;
+         } else {
+                len = t->len;
+                rx_buf = t->rx_buf;
+        }
+
+        /* prepare dummy transfer to generate SPI clocks */
+        dummy = kzalloc(len, GFP_KERNEL);
+        if (!dummy) {
+                ret = -ENOMEM;
+                goto end_nomap;
+        }
+        if (!rspi_dma_map_sg(&sg_dummy, dummy, len, rspi->chan_tx,
+                             DMA_TO_DEVICE)) {
+                ret = -EFAULT;
+                goto end_nomap;
+        }
+        desc_dummy = dmaengine_prep_slave_sg(rspi->chan_tx, &sg_dummy, 1,
+                        DMA_TO_DEVICE, DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+        if (!desc_dummy) {
+                ret = -EIO;
+                goto end_dummy_mapped;
+        }
+
+        /* prepare receive transfer */
+        if (!rspi_dma_map_sg(&sg, rx_buf, len, rspi->chan_rx,
+                             DMA_FROM_DEVICE)) {
+                ret = -EFAULT;
+                goto end_dummy_mapped;
+
+        }
+        desc = dmaengine_prep_slave_sg(rspi->chan_rx, &sg, 1, DMA_FROM_DEVICE,
+                                       DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+        if (!desc) {
+                ret = -EIO;
+                goto end;
+        }
+
+        rspi_receive_init(rspi);
+
+        /*
+         * DMAC needs SPTIE, but if SPTIE is set, this IRQ routine will be
+         * called. So, this driver disables the IRQ while DMA transfer.
+         */
+        disable_irq(rspi->irq);
+
+        rspi_write8(rspi, rspi_read8(rspi, RSPI_SPCR) & ~SPCR_TXMD, RSPI_SPCR);
+        rspi_enable_irq(rspi, SPCR_SPTIE | SPCR_SPRIE);
+        rspi->dma_callbacked = 0;
+
+        desc->callback = rspi_dma_complete;
+        desc->callback_param = rspi;
+        dmaengine_submit(desc);
+        dma_async_issue_pending(rspi->chan_rx);
+
+        desc_dummy->callback = NULL;    /* No callback */
+        dmaengine_submit(desc_dummy);
+        dma_async_issue_pending(rspi->chan_tx);
+
+        ret = wait_event_interruptible_timeout(rspi->wait,
+                                               rspi->dma_callbacked, HZ);
+        if (ret > 0 && rspi->dma_callbacked)
+                ret = 0;
+        else if (!ret)
+                ret = -ETIMEDOUT;
+        rspi_disable_irq(rspi, SPCR_SPTIE | SPCR_SPRIE);
+
+        enable_irq(rspi->irq);
+
+end:
+        rspi_dma_unmap_sg(&sg, rspi->chan_rx, DMA_FROM_DEVICE);
+end_dummy_mapped:
+        rspi_dma_unmap_sg(&sg_dummy, rspi->chan_tx, DMA_TO_DEVICE);
+end_nomap:
+        if (rspi->dma_width_16bit) {
+                if (!ret)
+                        rspi_memory_from_8bit(t->rx_buf, rx_buf, t->len);
+                kfree(rx_buf);
+        }
+        kfree(dummy);
+
+        return ret;
+}
+
+static int rspi_is_dma(struct rspi_data *rspi, struct spi_transfer *t)
+{
+        if (t->tx_buf && rspi->chan_tx)
+                return 1;
+        /* If the module receives data by DMAC, it also needs TX DMAC */
+        if (t->rx_buf && rspi->chan_tx && rspi->chan_rx)
+                return 1;
+
+        return 0;
+}
+
 static void rspi_work(struct work_struct *work)
 {
         struct rspi_data *rspi = container_of(work, struct rspi_data, ws);
@@ -325,12 +576,18 @@ static void rspi_work(struct work_struct *work)
 
                 list_for_each_entry(t, &mesg->transfers, transfer_list) {
                         if (t->tx_buf) {
-                                ret = rspi_send_pio(rspi, mesg, t);
+                                if (rspi_is_dma(rspi, t))
+                                        ret = rspi_send_dma(rspi, t);
+                                else
+                                        ret = rspi_send_pio(rspi, mesg, t);
                                 if (ret < 0)
                                         goto error;
                         }
                         if (t->rx_buf) {
-                                ret = rspi_receive_pio(rspi, mesg, t);
+                                if (rspi_is_dma(rspi, t))
+                                        ret = rspi_receive_dma(rspi, t);
+                                else
+                                        ret = rspi_receive_pio(rspi, mesg, t);
                                 if (ret < 0)
                                         goto error;
                         }
@@ -406,11 +663,58 @@ static irqreturn_t rspi_irq(int irq, void *_sr)
         return ret;
 }
 
+static bool rspi_filter(struct dma_chan *chan, void *filter_param)
+{
+        chan->private = filter_param;
+        return true;
+}
+
+static void __devinit rspi_request_dma(struct rspi_data *rspi,
+                                       struct platform_device *pdev)
+{
+        struct rspi_plat_data *rspi_pd = pdev->dev.platform_data;
+        dma_cap_mask_t mask;
+
+        if (!rspi_pd)
+                return;
+
+        rspi->dma_width_16bit = rspi_pd->dma_width_16bit;
+
+        /* If the module receives data by DMAC, it also needs TX DMAC */
+        if (rspi_pd->dma_rx_id && rspi_pd->dma_tx_id) {
+                dma_cap_zero(mask);
+                dma_cap_set(DMA_SLAVE, mask);
+                rspi->dma_rx.slave_id = rspi_pd->dma_rx_id;
+                rspi->chan_rx = dma_request_channel(mask, rspi_filter,
+                                                    &rspi->dma_rx);
+                if (rspi->chan_rx)
+                        dev_info(&pdev->dev, "Use DMA when rx.\n");
+        }
+        if (rspi_pd->dma_tx_id) {
+                dma_cap_zero(mask);
+                dma_cap_set(DMA_SLAVE, mask);
+                rspi->dma_tx.slave_id = rspi_pd->dma_tx_id;
+                rspi->chan_tx = dma_request_channel(mask, rspi_filter,
+                                                    &rspi->dma_tx);
+                if (rspi->chan_tx)
+                        dev_info(&pdev->dev, "Use DMA when tx\n");
+        }
+}
+
+static void __devexit rspi_release_dma(struct rspi_data *rspi)
+{
+        if (rspi->chan_tx)
+                dma_release_channel(rspi->chan_tx);
+        if (rspi->chan_rx)
+                dma_release_channel(rspi->chan_rx);
+}
+
 static int __devexit rspi_remove(struct platform_device *pdev)
 {
         struct rspi_data *rspi = dev_get_drvdata(&pdev->dev);
 
         spi_unregister_master(rspi->master);
+        rspi_release_dma(rspi);
         free_irq(platform_get_irq(pdev, 0), rspi);
         clk_put(rspi->clk);
         iounmap(rspi->addr);
@@ -483,6 +787,9 @@ static int __devinit rspi_probe(struct platform_device *pdev)
                 goto error3;
         }
 
+        rspi->irq = irq;
+        rspi_request_dma(rspi, pdev);
+
         ret = spi_register_master(master);
         if (ret < 0) {
                 dev_err(&pdev->dev, "spi_register_master error.\n");
@@ -494,6 +801,7 @@ static int __devinit rspi_probe(struct platform_device *pdev)
         return 0;
 
 error4:
+        rspi_release_dma(rspi);
         free_irq(irq, rspi);
 error3:
         clk_put(rspi->clk);
diff --git a/include/linux/spi/rspi.h b/include/linux/spi/rspi.h
new file mode 100644
index 000000000000..900f0e328235
--- /dev/null
+++ b/include/linux/spi/rspi.h
@@ -0,0 +1,31 @@
+/*
+ * Renesas SPI driver
+ *
+ * Copyright (C) 2012  Renesas Solutions Corp.
+ *
+ * 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; version 2 of the License.
+ *
+ * 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 St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ */
+
+#ifndef __LINUX_SPI_RENESAS_SPI_H__
+#define __LINUX_SPI_RENESAS_SPI_H__
+
+struct rspi_plat_data {
+        unsigned int dma_tx_id;
+        unsigned int dma_rx_id;
+
+        unsigned dma_width_16bit:1;     /* DMAC read/write width = 16-bit */
+};
+
+#endif