serial: pl011: use generic DMA slave configuration if possible

With the new OF DMA binding, it is possible to completely avoid the
need for platform_data for configuring a DMA channel. In cases where the
platform has already been converted, calling dma_request_slave_channel
should get all the necessary information from the device tree.

This also adds a binding document specific to the pl011 controller,
and extends the generic primecell binding to mention "dmas" and other
common properties.

Like the patch that converts the dw_dma controller, this is completely
untested and is looking for someone to try it out.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: devicetree-discuss@lists.ozlabs.org
Cc: linux-arm-kernel@lists.infradead.org

diff --git a/Documentation/devicetree/bindings/arm/primecell.txt b/Documentation/devicetree/bindings/arm/primecell.txt
index 64fc82b..0df6aca 100644 (file)
--- a/Documentation/devicetree/bindings/arm/primecell.txt
+++ b/Documentation/devicetree/bindings/arm/primecell.txt
@@ -16,14 +16,31 @@ Optional properties:
 - clocks : From common clock binding. First clock is phandle to clock for apb
        pclk. Additional clocks are optional and specific to those peripherals.
 - clock-names : From common clock binding. Shall be "apb_pclk" for first clock.
+- dmas : From common DMA binding. If present, refers to one or more dma channels.
+- dma-names : From common DMA binding, needs to match the 'dmas' property.
+              Devices with exactly one receive and transmit channel shall name
+              these "rx" and "tx", respectively.
+- pinctrl-<n> : Pinctrl states as described in bindings/pinctrl/pinctrl-bindings.txt
+- pinctrl-names : Names corresponding to the numbered pinctrl states
+- interrupts : one or more interrupt specifiers
+- interrupt-names : names corresponding to the interrupts properties
 
 Example:
 
 serial@fff36000 {
        compatible = "arm,pl011", "arm,primecell";
        arm,primecell-periphid = <0x00341011>;
+
        clocks = <&pclk>;
        clock-names = "apb_pclk";
-       
+
+       dmas = <&dma-controller 4>, <&dma-controller 5>;
+       dma-names = "rx", "tx"; 
+
+       pinctrl-0 = <&uart0_default_mux>, <&uart0_default_mode>;
+       pinctrl-1 = <&uart0_sleep_mode>;
+       pinctrl-names = "default","sleep";
+
+       interrupts = <0 11 0x4>;
 };
 

diff --git a/Documentation/devicetree/bindings/serial/pl011.txt b/Documentation/devicetree/bindings/serial/pl011.txt
new file mode 100644 (file)
index 0000000..5d2e840
--- /dev/null
+++ b/Documentation/devicetree/bindings/serial/pl011.txt
@@ -0,0 +1,17 @@
+* ARM AMBA Primecell PL011 serial UART
+
+Required properties:
+- compatible: must be "arm,primecell", "arm,pl011"
+- reg: exactly one register range with length 0x1000
+- interrupts: exactly one interrupt specifier
+
+Optional properties:
+- pinctrl: When present, must have one state named "sleep"
+          and one state named "default"
+- clocks:  When present, must refer to exactly one clock named
+          "apb_pclk"
+- dmas:           When present, may have one or two dma channels.
+          The first one must be named "rx", the second one
+          must be named "tx".
+
+See also bindings/arm/primecell.txt

diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 3ea5408..c25b00e 100644 (file)
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -245,7 +245,7 @@ static void pl011_sgbuf_free(struct dma_chan *chan, struct pl011_sgbuf *sg,
        }
 }
 
-static void pl011_dma_probe_initcall(struct uart_amba_port *uap)
+static void pl011_dma_probe_initcall(struct device *dev, struct uart_amba_port *uap)
 {
        /* DMA is the sole user of the platform data right now */
        struct amba_pl011_data *plat = uap->port.dev->platform_data;
@@ -259,20 +259,25 @@ static void pl011_dma_probe_initcall(struct uart_amba_port *uap)
        struct dma_chan *chan;
        dma_cap_mask_t mask;
 
-       /* We need platform data */
-       if (!plat || !plat->dma_filter) {
-               dev_info(uap->port.dev, "no DMA platform data\n");
-               return;
-       }
+       chan = dma_request_slave_channel(dev, "tx");
 
-       /* Try to acquire a generic DMA engine slave TX channel */
-       dma_cap_zero(mask);
-       dma_cap_set(DMA_SLAVE, mask);
-
-       chan = dma_request_channel(mask, plat->dma_filter, plat->dma_tx_param);
        if (!chan) {
-               dev_err(uap->port.dev, "no TX DMA channel!\n");
-               return;
+               /* We need platform data */
+               if (!plat || !plat->dma_filter) {
+                       dev_info(uap->port.dev, "no DMA platform data\n");
+                       return;
+               }
+
+               /* Try to acquire a generic DMA engine slave TX channel */
+               dma_cap_zero(mask);
+               dma_cap_set(DMA_SLAVE, mask);
+
+               chan = dma_request_channel(mask, plat->dma_filter,
+                                               plat->dma_tx_param);
+               if (!chan) {
+                       dev_err(uap->port.dev, "no TX DMA channel!\n");
+                       return;
+               }
        }
 
        dmaengine_slave_config(chan, &tx_conf);
@@ -282,7 +287,18 @@ static void pl011_dma_probe_initcall(struct uart_amba_port *uap)
                 dma_chan_name(uap->dmatx.chan));
 
        /* Optionally make use of an RX channel as well */
-       if (plat->dma_rx_param) {
+       chan = dma_request_slave_channel(dev, "rx");
+       
+       if (!chan && plat->dma_rx_param) {
+               chan = dma_request_channel(mask, plat->dma_filter, plat->dma_rx_param);
+
+               if (!chan) {
+                       dev_err(uap->port.dev, "no RX DMA channel!\n");
+                       return;
+               }
+       }
+
+       if (chan) {
                struct dma_slave_config rx_conf = {
                        .src_addr = uap->port.mapbase + UART01x_DR,
                        .src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE,
@@ -291,12 +307,6 @@ static void pl011_dma_probe_initcall(struct uart_amba_port *uap)
                        .device_fc = false,
                };
 
-               chan = dma_request_channel(mask, plat->dma_filter, plat->dma_rx_param);
-               if (!chan) {
-                       dev_err(uap->port.dev, "no RX DMA channel!\n");
-                       return;
-               }
-
                dmaengine_slave_config(chan, &rx_conf);
                uap->dmarx.chan = chan;
 
@@ -315,6 +325,7 @@ static void pl011_dma_probe_initcall(struct uart_amba_port *uap)
 struct dma_uap {
        struct list_head node;
        struct uart_amba_port *uap;
+       struct device *dev;
 };
 
 static LIST_HEAD(pl011_dma_uarts);
@@ -325,7 +336,7 @@ static int __init pl011_dma_initcall(void)
 
        list_for_each_safe(node, tmp, &pl011_dma_uarts) {
                struct dma_uap *dmau = list_entry(node, struct dma_uap, node);
-               pl011_dma_probe_initcall(dmau->uap);
+               pl011_dma_probe_initcall(dmau->dev, dmau->uap);
                list_del(node);
                kfree(dmau);
        }
@@ -334,18 +345,19 @@ static int __init pl011_dma_initcall(void)
 
 device_initcall(pl011_dma_initcall);
 
-static void pl011_dma_probe(struct uart_amba_port *uap)
+static void pl011_dma_probe(struct device *dev, struct uart_amba_port *uap)
 {
        struct dma_uap *dmau = kzalloc(sizeof(struct dma_uap), GFP_KERNEL);
        if (dmau) {
                dmau->uap = uap;
+               dmau->dev = dev;
                list_add_tail(&dmau->node, &pl011_dma_uarts);
        }
 }
 #else
-static void pl011_dma_probe(struct uart_amba_port *uap)
+static void pl011_dma_probe(struct device *dev, struct uart_amba_port *uap)
 {
-       pl011_dma_probe_initcall(uap);
+       pl011_dma_probe_initcall(dev, uap);
 }
 #endif
 
@@ -2020,7 +2032,7 @@ static int pl011_probe(struct amba_device *dev, const struct amba_id *id)
        uap->port.ops = &amba_pl011_pops;
        uap->port.flags = UPF_BOOT_AUTOCONF;
        uap->port.line = i;
-       pl011_dma_probe(uap);
+       pl011_dma_probe(&dev->dev, uap);
 
        /* Ensure interrupts from this UART are masked and cleared */
        writew(0, uap->port.membase + UART011_IMSC);