Commit 787b0c1f authored by Arnd Bergmann's avatar Arnd Bergmann
Browse files

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: default avatarArnd Bergmann <arnd@arndb.de>
Acked-by: default avatarGrant Likely <grant.likely@secretlab.ca>
Acked-by: default avatarGreg 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
parent dc715452

Documentation/devicetree/bindings/arm/primecell.txt

+18 −1
Original line number Diff line number Diff line
@@ -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>;

};

Documentation/devicetree/bindings/serial/pl011.txt

0 → 100644
+17 −0
Original line number Diff line number Diff line 
* 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

drivers/tty/serial/amba-pl011.c

+37 −25
Original line number Diff line number Diff line
@@ -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;
@@ -259,6 +259,9 @@ static void pl011_dma_probe_initcall(struct uart_amba_port *uap) 
	struct dma_chan *chan;

	dma_cap_mask_t mask;



	chan = dma_request_slave_channel(dev, "tx");



	if (!chan) {

		/* We need platform data */

		if (!plat || !plat->dma_filter) {

			dev_info(uap->port.dev, "no DMA platform data\n");
@@ -269,11 +272,13 @@ static void pl011_dma_probe_initcall(struct uart_amba_port *uap) 
		dma_cap_zero(mask);

		dma_cap_set(DMA_SLAVE, mask);



	chan = dma_request_channel(mask, plat->dma_filter, plat->dma_tx_param);

		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);

	uap->dmatx.chan = chan;
@@ -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);

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