Add new UART driver with DMA support for Aspeed AST2600 SoCs.
The drivers mainly prepare the dma instance based on the 8250_dma
implementation to leverage the AST2600 UART DMA (UDMA) engine.
Signed-off-by: Chia-Wei Wang <chiawei_wang@xxxxxxxxxxxxxx>
---
drivers/tty/serial/8250/8250_aspeed.c | 224 ++++++++++++++++++++++++++
drivers/tty/serial/8250/Kconfig | 8 +
drivers/tty/serial/8250/Makefile | 1 +
3 files changed, 233 insertions(+)
create mode 100644 drivers/tty/serial/8250/8250_aspeed.c
diff --git a/drivers/tty/serial/8250/8250_aspeed.c b/drivers/tty/serial/8250/8250_aspeed.c
new file mode 100644
index 000000000000..04d0bf6fba28
--- /dev/null
+++ b/drivers/tty/serial/8250/8250_aspeed.c
@@ -0,0 +1,224 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) ASPEED Technology Inc.
+ */
+#include <linux/device.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/serial_8250.h>
+#include <linux/serial_reg.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/clk.h>
+#include <linux/reset.h>
+#include <linux/dma-mapping.h>
+#include <linux/circ_buf.h>
+#include <linux/tty_flip.h>
+#include <linux/pm_runtime.h>
+
+#include "8250.h"
+
+#define DEVICE_NAME "aspeed-uart"
+
+struct ast8250_data {
+ int line;
+ int irq;
+ u8 __iomem *regs;
+ struct reset_control *rst;
+ struct clk *clk;
+#ifdef CONFIG_SERIAL_8250_DMA
+ struct uart_8250_dma dma;
+#endif
+};
+
+#ifdef CONFIG_SERIAL_8250_DMA
+static int ast8250_rx_dma(struct uart_8250_port *p);
+
+static void ast8250_rx_dma_complete(void *param)
+{
+ struct uart_8250_port *p = param;
+ struct uart_8250_dma *dma = p->dma;
+ struct tty_port *tty_port = &p->port.state->port;
+ struct dma_tx_state state;
+ int count;
+
+ dmaengine_tx_status(dma->rxchan, dma->rx_cookie, &state);
+
+ count = dma->rx_size - state.residue;
+
+ tty_insert_flip_string(tty_port, dma->rx_buf, count);
+ p->port.icount.rx += count;
+
+ tty_flip_buffer_push(tty_port);
+
+ ast8250_rx_dma(p);
+}
+
+static int ast8250_rx_dma(struct uart_8250_port *p)
+{
+ struct uart_8250_dma *dma = p->dma;
+ struct dma_async_tx_descriptor *tx;
+
+ tx = dmaengine_prep_slave_single(dma->rxchan, dma->rx_addr,
+ dma->rx_size, DMA_DEV_TO_MEM,
+ DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+ if (!tx)
+ return -EBUSY;
+
+ tx->callback = ast8250_rx_dma_complete;
+ tx->callback_param = p;
+
+ dma->rx_cookie = dmaengine_submit(tx);
+
+ dma_async_issue_pending(dma->rxchan);
+
+ return 0;
+}
+#endif
+
+static int ast8250_handle_irq(struct uart_port *port)
+{
+ return serial8250_handle_irq(port, serial_port_in(port, UART_IIR));
+}
+
+static int ast8250_startup(struct uart_port *port)
+{
+#ifdef CONFIG_SERIAL_8250_DMA
+ int rc;
+ struct uart_8250_port *up = up_to_u8250p(port);
+
+ rc = serial8250_do_startup(port);
+ if (rc)
+ return rc;
+
+ /*
+ * The default RX DMA is launched upon rising DR bit.
+ *
+ * However, this can result in byte lost if UART FIFO has
+ * been overruned before the DMA engine gets prepared and
+ * read the data out. This is especially common when UART
+ * DMA is used for file transfer. Thus we initiate RX DMA
+ * as early as possible.
+ */
+ if (up->dma)
+ return ast8250_rx_dma(up);
+
+ return 0;
+#else
+ return serial8250_do_startup(port);
+#endif
+}
+
+static void ast8250_shutdown(struct uart_port *port)
+{
+ return serial8250_do_shutdown(port);
+}
+
+static int ast8250_probe(struct platform_device *pdev)
+{
+ int rc;
+ struct uart_8250_port uart = {};
+ struct uart_port *port = &uart.port;
+ struct device *dev = &pdev->dev;
+ struct ast8250_data *data;
+ struct resource *res;
+
+ data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+
+ data->irq = platform_get_irq(pdev, 0);
+ if (data->irq < 0)
+ return data->irq;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (res == NULL) {
+ dev_err(dev, "failed to get register base\n");
+ return -ENODEV;
+ }
+
+ data->regs = devm_ioremap(dev, res->start, resource_size(res));
+ if (IS_ERR(data->regs)) {
+ dev_err(dev, "failed to map registers\n");
+ return PTR_ERR(data->regs);
+ }
+
+ data->clk = devm_clk_get(dev, NULL);
+ if (IS_ERR(data->clk)) {
+ dev_err(dev, "failed to get clocks\n");
+ return -ENODEV;
+ }
+
+ rc = clk_prepare_enable(data->clk);
+ if (rc) {
+ dev_err(dev, "failed to enable clock\n");
+ return rc;
+ }
+
+ data->rst = devm_reset_control_get_optional_exclusive(dev, NULL);
+ if (!IS_ERR(data->rst))
+ reset_control_deassert(data->rst);
+
+ spin_lock_init(&port->lock);
+ port->dev = dev;
+ port->type = PORT_16550A;
+ port->irq = data->irq;
+ port->line = of_alias_get_id(dev->of_node, "serial");
+ port->handle_irq = ast8250_handle_irq;
+ port->mapbase = res->start;
+ port->mapsize = resource_size(res);
+ port->membase = data->regs;
+ port->uartclk = clk_get_rate(data->clk);
+ port->regshift = 2;
+ port->iotype = UPIO_MEM32;
+ port->flags = UPF_FIXED_TYPE | UPF_FIXED_PORT | UPF_SHARE_IRQ;
+ port->startup = ast8250_startup;
+ port->shutdown = ast8250_shutdown;
+ port->private_data = data;
+#ifdef CONFIG_SERIAL_8250_DMA
+ data->dma.rxconf.src_maxburst = UART_XMIT_SIZE;
+ data->dma.txconf.dst_maxburst = UART_XMIT_SIZE;
+ uart.dma = &data->dma;
+#endif
+
+ data->line = serial8250_register_8250_port(&uart);
+ if (data->line < 0) {
+ dev_err(dev, "failed to register 8250 port\n");
+ return data->line;
+ }
+
+ platform_set_drvdata(pdev, data);
+
+ return 0;
+}
+
+static int ast8250_remove(struct platform_device *pdev)
+{
+ struct ast8250_data *data = platform_get_drvdata(pdev);
+
+ serial8250_unregister_port(data->line);
+
+ return 0;
+}
+
+static const struct of_device_id ast8250_of_match[] = {
+ { .compatible = "aspeed,ast2600-uart" },
+ { },
+};
+
+static struct platform_driver ast8250_platform_driver = {
+ .driver = {
+ .name = DEVICE_NAME,
+ .of_match_table = ast8250_of_match,
+ },
+ .probe = ast8250_probe,
+ .remove = ast8250_remove,
+};
+
+module_platform_driver(ast8250_platform_driver);
+
+MODULE_AUTHOR("Chia-Wei Wang <chiawei_wang@xxxxxxxxxxxxxx>");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Aspeed 8250 UART Driver with DMA support");
diff --git a/drivers/tty/serial/8250/Kconfig b/drivers/tty/serial/8250/Kconfig
index 978dc196c29b..f8a2231816c4 100644
--- a/drivers/tty/serial/8250/Kconfig
+++ b/drivers/tty/serial/8250/Kconfig
@@ -253,6 +253,14 @@ config SERIAL_8250_ACCENT
To compile this driver as a module, choose M here: the module
will be called 8250_accent.
+config SERIAL_8250_ASPEED
+ tristate "Aspeed UART"
+ depends on ARCH_ASPEED && SERIAL_8250
+ help
+ If you have a system using an Aspeed AST26xx SoCs and wish to
+ make use of its 16550A-compatible UART devices with DMA support,
+ say Y to this option. If unsure, say N.
+
config SERIAL_8250_ASPEED_VUART
tristate "Aspeed Virtual UART"
depends on SERIAL_8250
diff --git a/drivers/tty/serial/8250/Makefile b/drivers/tty/serial/8250/Makefile
index 4fc2fc1f41b6..7b959e652b67 100644
--- a/drivers/tty/serial/8250/Makefile
+++ b/drivers/tty/serial/8250/Makefile
@@ -20,6 +20,7 @@ obj-$(CONFIG_SERIAL_8250_HP300) += 8250_hp300.o
obj-$(CONFIG_SERIAL_8250_CS) += serial_cs.o
obj-$(CONFIG_SERIAL_8250_ACORN) += 8250_acorn.o
obj-$(CONFIG_SERIAL_8250_ASPEED_VUART) += 8250_aspeed_vuart.o
+obj-$(CONFIG_SERIAL_8250_ASPEED) += 8250_aspeed.o
obj-$(CONFIG_SERIAL_8250_BCM2835AUX) += 8250_bcm2835aux.o
obj-$(CONFIG_SERIAL_8250_CONSOLE) += 8250_early.o
obj-$(CONFIG_SERIAL_8250_FOURPORT) += 8250_fourport.o
--
2.25.1
