at_hdmac: move to generic DMA binding

Update at_hdmac driver to support generic DMA device tree binding. Devices
can still request channel with dma_request_channel() then it doesn't break
DMA for non DT boards.

Signed-off-by: Ludovic Desroches <ludovic.desroches@atmel.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Acked-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

3 files changed, 121 insertions, 11 deletions

diff --git a/Documentation/devicetree/bindings/dma/atmel-dma.txt b/Documentation/devicetree/bindings/dma/atmel-dma.txt
index 3c046ee6e8b5..c80e8a3402f0 100644
--- a/Documentation/devicetree/bindings/dma/atmel-dma.txt
+++ b/Documentation/devicetree/bindings/dma/atmel-dma.txt
@@ -1,14 +1,39 @@
 * Atmel Direct Memory Access Controller (DMA)
 
 Required properties:
-- compatible: Should be "atmel,<chip>-dma"
-- reg: Should contain DMA registers location and length
-- interrupts: Should contain DMA interrupt
+- compatible: Should be "atmel,<chip>-dma".
+- reg: Should contain DMA registers location and length.
+- interrupts: Should contain DMA interrupt.
+- #dma-cells: Must be <2>, used to represent the number of integer cells in
+the dmas property of client devices.
 
-Examples:
+Example:
 
-dma@ffffec00 {
+dma0: dma@ffffec00 {
         compatible = "atmel,at91sam9g45-dma";
         reg = <0xffffec00 0x200>;
         interrupts = <21>;
+        #dma-cells = <2>;
+};
+
+DMA clients connected to the Atmel DMA controller must use the format
+described in the dma.txt file, using a three-cell specifier for each channel:
+a phandle plus two interger cells.
+The three cells in order are:
+
+1. A phandle pointing to the DMA controller.
+2. The memory interface (16 most significant bits), the peripheral interface
+(16 less significant bits).
+3. The peripheral identifier for the hardware handshaking interface. The
+identifier can be different for tx and rx.
+
+Example:
+
+i2c0@i2c@f8010000 {
+        compatible = "atmel,at91sam9x5-i2c";
+        reg = <0xf8010000 0x100>;
+        interrupts = <9 4 6>;
+        dmas = <&dma0 1 7>,
+               <&dma0 1 8>;
+        dma-names = "tx", "rx";
 };
diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c
index 841546776159..3502c412caf9 100644
--- a/drivers/dma/at_hdmac.c
+++ b/drivers/dma/at_hdmac.c
@@ -24,6 +24,7 @@
 #include <linux/slab.h>
 #include <linux/of.h>
 #include <linux/of_device.h>
+#include <linux/of_dma.h>
 
 #include "at_hdmac_regs.h"
 #include "dmaengine.h"
@@ -676,7 +677,7 @@ atc_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
                 ctrlb |=  ATC_DST_ADDR_MODE_FIXED
                         | ATC_SRC_ADDR_MODE_INCR
                         | ATC_FC_MEM2PER
-                        | ATC_SIF(AT_DMA_MEM_IF) | ATC_DIF(AT_DMA_PER_IF);
+                        | ATC_SIF(atchan->mem_if) | ATC_DIF(atchan->per_if);
                 reg = sconfig->dst_addr;
                 for_each_sg(sgl, sg, sg_len, i) {
                         struct at_desc  *desc;
@@ -715,7 +716,7 @@ atc_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
                 ctrlb |=  ATC_DST_ADDR_MODE_INCR
                         | ATC_SRC_ADDR_MODE_FIXED
                         | ATC_FC_PER2MEM
-                        | ATC_SIF(AT_DMA_PER_IF) | ATC_DIF(AT_DMA_MEM_IF);
+                        | ATC_SIF(atchan->per_if) | ATC_DIF(atchan->mem_if);
 
                 reg = sconfig->src_addr;
                 for_each_sg(sgl, sg, sg_len, i) {
@@ -821,8 +822,8 @@ atc_dma_cyclic_fill_desc(struct dma_chan *chan, struct at_desc *desc,
                 desc->lli.ctrlb = ATC_DST_ADDR_MODE_FIXED
                                 | ATC_SRC_ADDR_MODE_INCR
                                 | ATC_FC_MEM2PER
-                                | ATC_SIF(AT_DMA_MEM_IF)
-                                | ATC_DIF(AT_DMA_PER_IF);
+                                | ATC_SIF(atchan->mem_if)
+                                | ATC_DIF(atchan->per_if);
                 break;
 
         case DMA_DEV_TO_MEM:
@@ -832,8 +833,8 @@ atc_dma_cyclic_fill_desc(struct dma_chan *chan, struct at_desc *desc,
                 desc->lli.ctrlb = ATC_DST_ADDR_MODE_INCR
                                 | ATC_SRC_ADDR_MODE_FIXED
                                 | ATC_FC_PER2MEM
-                                | ATC_SIF(AT_DMA_PER_IF)
-                                | ATC_DIF(AT_DMA_MEM_IF);
+                                | ATC_SIF(atchan->per_if)
+                                | ATC_DIF(atchan->mem_if);
                 break;
 
         default:
@@ -1189,6 +1190,67 @@ static void atc_free_chan_resources(struct dma_chan *chan)
         dev_vdbg(chan2dev(chan), "free_chan_resources: done\n");
 }
 
+#ifdef CONFIG_OF
+static bool at_dma_filter(struct dma_chan *chan, void *slave)
+{
+        struct at_dma_slave *atslave = slave;
+
+        if (atslave->dma_dev == chan->device->dev) {
+                chan->private = atslave;
+                return true;
+        } else {
+                return false;
+        }
+}
+
+static struct dma_chan *at_dma_xlate(struct of_phandle_args *dma_spec,
+                                     struct of_dma *of_dma)
+{
+        struct dma_chan *chan;
+        struct at_dma_chan *atchan;
+        struct at_dma_slave *atslave;
+        dma_cap_mask_t mask;
+        unsigned int per_id;
+        struct platform_device *dmac_pdev;
+
+        if (dma_spec->args_count != 2)
+                return NULL;
+
+        dmac_pdev = of_find_device_by_node(dma_spec->np);
+
+        dma_cap_zero(mask);
+        dma_cap_set(DMA_SLAVE, mask);
+
+        atslave = devm_kzalloc(&dmac_pdev->dev, sizeof(*atslave), GFP_KERNEL);
+        if (!atslave)
+                return NULL;
+        /*
+         * We can fill both SRC_PER and DST_PER, one of these fields will be
+         * ignored depending on DMA transfer direction.
+         */
+        per_id = dma_spec->args[1];
+        atslave->cfg = ATC_FIFOCFG_HALFFIFO | ATC_DST_H2SEL_HW
+                      | ATC_SRC_H2SEL_HW | ATC_DST_PER(per_id)
+                      | ATC_SRC_PER(per_id);
+        atslave->dma_dev = &dmac_pdev->dev;
+
+        chan = dma_request_channel(mask, at_dma_filter, atslave);
+        if (!chan)
+                return NULL;
+
+        atchan = to_at_dma_chan(chan);
+        atchan->per_if = dma_spec->args[0] & 0xff;
+        atchan->mem_if = (dma_spec->args[0] >> 16) & 0xff;
+
+        return chan;
+}
+#else
+static struct dma_chan *at_dma_xlate(struct of_phandle_args *dma_spec,
+                                     struct of_dma *of_dma)
+{
+        return NULL;
+}
+#endif
 
 /*--  Module Management  -----------------------------------------------*/
 
@@ -1343,6 +1405,8 @@ static int __init at_dma_probe(struct platform_device *pdev)
         for (i = 0; i < plat_dat->nr_channels; i++) {
                 struct at_dma_chan      *atchan = &atdma->chan[i];
 
+                atchan->mem_if = AT_DMA_MEM_IF;
+                atchan->per_if = AT_DMA_PER_IF;
                 atchan->chan_common.device = &atdma->dma_common;
                 dma_cookie_init(&atchan->chan_common);
                 list_add_tail(&atchan->chan_common.device_node,
@@ -1389,8 +1453,25 @@ static int __init at_dma_probe(struct platform_device *pdev)
 
         dma_async_device_register(&atdma->dma_common);
 
+        /*
+         * Do not return an error if the dmac node is not present in order to
+         * not break the existing way of requesting channel with
+         * dma_request_channel().
+         */
+        if (pdev->dev.of_node) {
+                err = of_dma_controller_register(pdev->dev.of_node,
+                                                 at_dma_xlate, atdma);
+                if (err) {
+                        dev_err(&pdev->dev, "could not register of_dma_controller\n");
+                        goto err_of_dma_controller_register;
+                }
+        }
+
         return 0;
 
+err_of_dma_controller_register:
+        dma_async_device_unregister(&atdma->dma_common);
+        dma_pool_destroy(atdma->dma_desc_pool);
 err_pool_create:
         platform_set_drvdata(pdev, NULL);
         free_irq(platform_get_irq(pdev, 0), atdma);
diff --git a/drivers/dma/at_hdmac_regs.h b/drivers/dma/at_hdmac_regs.h
index 0eb3c1388667..c604d26fd4d3 100644
--- a/drivers/dma/at_hdmac_regs.h
+++ b/drivers/dma/at_hdmac_regs.h
@@ -220,6 +220,8 @@ enum atc_status {
  * @device: parent device
  * @ch_regs: memory mapped register base
  * @mask: channel index in a mask
+ * @per_if: peripheral interface
+ * @mem_if: memory interface
  * @status: transmit status information from irq/prep* functions
  *                to tasklet (use atomic operations)
  * @tasklet: bottom half to finish transaction work
@@ -238,6 +240,8 @@ struct at_dma_chan {
         struct at_dma           *device;
         void __iomem            *ch_regs;
         u8                      mask;
+        u8                      per_if;
+        u8                      mem_if;
         unsigned long           status;
         struct tasklet_struct   tasklet;
         u32                     save_cfg;