[PATCH 3/4] serial: 8250: Add Aspeed UART driver
Chia-Wei Wang
chiawei_wang at aspeedtech.com
Fri Feb 10 18:26:42 AEDT 2023
Add the driver for Aspeed UART/VUART devices, which are 16550A
compatible. It is an wrapper to cover the generic 16550A operation
while exetending DMA feature for the devices.
Signed-off-by: Chia-Wei Wang <chiawei_wang at aspeedtech.com>
---
drivers/tty/serial/8250/8250_aspeed.c | 502 ++++++++++++++++++++++++++
drivers/tty/serial/8250/Kconfig | 8 +
drivers/tty/serial/8250/Makefile | 1 +
3 files changed, 511 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..2eaa59ee6d27
--- /dev/null
+++ b/drivers/tty/serial/8250/8250_aspeed.c
@@ -0,0 +1,502 @@
+// 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 <linux/soc/aspeed/aspeed-udma.h>
+
+#include "8250.h"
+
+#define DEVICE_NAME "aspeed-uart"
+
+/* offsets for the aspeed virtual uart registers */
+#define VUART_GCRA 0x20
+#define VUART_GCRA_VUART_EN BIT(0)
+#define VUART_GCRA_SIRQ_POLARITY BIT(1)
+#define VUART_GCRA_DISABLE_HOST_TX_DISCARD BIT(5)
+#define VUART_GCRB 0x24
+#define VUART_GCRB_HOST_SIRQ_MASK GENMASK(7, 4)
+#define VUART_GCRB_HOST_SIRQ_SHIFT 4
+#define VUART_ADDRL 0x28
+#define VUART_ADDRH 0x2c
+
+#define DMA_TX_BUFSZ PAGE_SIZE
+#define DMA_RX_BUFSZ (64 * 1024)
+
+struct uart_ops ast8250_pops;
+
+struct ast8250_vuart {
+ u32 port;
+ u32 sirq;
+ u32 sirq_pol;
+};
+
+struct ast8250_udma {
+ u32 ch;
+
+ u32 tx_rbsz;
+ u32 rx_rbsz;
+
+ dma_addr_t tx_addr;
+ dma_addr_t rx_addr;
+
+ struct circ_buf *tx_rb;
+ struct circ_buf *rx_rb;
+
+ bool tx_tmout_dis;
+ bool rx_tmout_dis;
+};
+
+struct ast8250_data {
+ int line;
+
+ u8 __iomem *regs;
+
+ bool is_vuart;
+ bool use_dma;
+
+ struct reset_control *rst;
+ struct clk *clk;
+
+ struct ast8250_vuart vuart;
+ struct ast8250_udma dma;
+};
+
+static void ast8250_dma_tx_complete(int tx_rb_rptr, void *id)
+{
+ u32 count;
+ unsigned long flags;
+ struct uart_port *port = (struct uart_port *)id;
+ struct ast8250_data *data = port->private_data;
+
+ spin_lock_irqsave(&port->lock, flags);
+
+ count = CIRC_CNT(tx_rb_rptr, port->state->xmit.tail, data->dma.tx_rbsz);
+ port->state->xmit.tail = tx_rb_rptr;
+ port->icount.tx += count;
+
+ if (uart_circ_chars_pending(&port->state->xmit) < WAKEUP_CHARS)
+ uart_write_wakeup(port);
+
+ spin_unlock_irqrestore(&port->lock, flags);
+}
+
+static void ast8250_dma_rx_complete(int rx_rb_wptr, void *id)
+{
+ unsigned long flags;
+ struct uart_port *up = (struct uart_port *)id;
+ struct tty_port *tp = &up->state->port;
+ struct ast8250_data *data = up->private_data;
+ struct ast8250_udma *dma = &data->dma;
+ struct circ_buf *rx_rb = dma->rx_rb;
+ u32 rx_rbsz = dma->rx_rbsz;
+ u32 count = 0;
+
+ spin_lock_irqsave(&up->lock, flags);
+
+ rx_rb->head = rx_rb_wptr;
+
+ dma_sync_single_for_cpu(up->dev,
+ dma->rx_addr, dma->rx_rbsz, DMA_FROM_DEVICE);
+
+ while (CIRC_CNT(rx_rb->head, rx_rb->tail, rx_rbsz)) {
+ count = CIRC_CNT_TO_END(rx_rb->head, rx_rb->tail, rx_rbsz);
+
+ tty_insert_flip_string(tp, rx_rb->buf + rx_rb->tail, count);
+
+ rx_rb->tail += count;
+ rx_rb->tail %= rx_rbsz;
+
+ up->icount.rx += count;
+ }
+
+ if (count) {
+ aspeed_udma_set_rx_rptr(data->dma.ch, rx_rb->tail);
+ tty_flip_buffer_push(tp);
+ }
+
+ spin_unlock_irqrestore(&up->lock, flags);
+}
+
+static void ast8250_dma_start_tx(struct uart_port *port)
+{
+ struct ast8250_data *data = port->private_data;
+ struct ast8250_udma *dma = &data->dma;
+ struct circ_buf *tx_rb = dma->tx_rb;
+
+ dma_sync_single_for_device(port->dev,
+ dma->tx_addr, dma->tx_rbsz, DMA_TO_DEVICE);
+
+ aspeed_udma_set_tx_wptr(dma->ch, tx_rb->head);
+}
+
+static void ast8250_dma_pops_hook(struct uart_port *port)
+{
+ static int first = 1;
+
+ if (first) {
+ ast8250_pops = *port->ops;
+ ast8250_pops.start_tx = ast8250_dma_start_tx;
+ }
+
+ first = 0;
+ port->ops = &ast8250_pops;
+}
+
+static void ast8250_vuart_init(struct ast8250_data *data)
+{
+ u8 reg;
+ struct ast8250_vuart *vuart = &data->vuart;
+
+ /* IO port address */
+ writeb((u8)(vuart->port >> 0), data->regs + VUART_ADDRL);
+ writeb((u8)(vuart->port >> 8), data->regs + VUART_ADDRH);
+
+ /* SIRQ number */
+ reg = readb(data->regs + VUART_GCRB);
+ reg &= ~VUART_GCRB_HOST_SIRQ_MASK;
+ reg |= ((vuart->sirq << VUART_GCRB_HOST_SIRQ_SHIFT) & VUART_GCRB_HOST_SIRQ_MASK);
+ writeb(reg, data->regs + VUART_GCRB);
+
+ /* SIRQ polarity */
+ reg = readb(data->regs + VUART_GCRA);
+ if (vuart->sirq_pol)
+ reg |= VUART_GCRA_SIRQ_POLARITY;
+ else
+ reg &= ~VUART_GCRA_SIRQ_POLARITY;
+ writeb(reg, data->regs + VUART_GCRA);
+}
+
+static void ast8250_vuart_set_host_tx_discard(struct ast8250_data *data, bool discard)
+{
+ u8 reg;
+
+ reg = readb(data->regs + VUART_GCRA);
+ if (discard)
+ reg &= ~VUART_GCRA_DISABLE_HOST_TX_DISCARD;
+ else
+ reg |= VUART_GCRA_DISABLE_HOST_TX_DISCARD;
+ writeb(reg, data->regs + VUART_GCRA);
+}
+
+static void ast8250_vuart_set_enable(struct ast8250_data *data, bool enable)
+{
+ u8 reg;
+
+ reg = readb(data->regs + VUART_GCRA);
+ if (enable)
+ reg |= VUART_GCRA_VUART_EN;
+ else
+ reg &= ~VUART_GCRA_VUART_EN;
+ writeb(reg, data->regs + VUART_GCRA);
+}
+
+static int ast8250_handle_irq(struct uart_port *port)
+{
+ u32 iir = port->serial_in(port, UART_IIR);
+
+ return serial8250_handle_irq(port, iir);
+}
+
+static int ast8250_startup(struct uart_port *port)
+{
+ int rc = 0;
+ struct ast8250_data *data = port->private_data;
+ struct ast8250_udma *dma;
+
+ if (data->is_vuart)
+ ast8250_vuart_set_host_tx_discard(data, false);
+
+ if (data->use_dma) {
+ dma = &data->dma;
+
+ dma->tx_rbsz = DMA_TX_BUFSZ;
+ dma->rx_rbsz = DMA_RX_BUFSZ;
+
+ /*
+ * We take the xmit buffer passed from upper layers as
+ * the DMA TX buffer and allocate a new buffer for the
+ * RX use.
+ *
+ * To keep the TX/RX operation consistency, we use the
+ * streaming DMA interface instead of the coherent one
+ */
+ dma->tx_rb = &port->state->xmit;
+ dma->rx_rb->buf = kzalloc(data->dma.rx_rbsz, GFP_KERNEL);
+ if (IS_ERR_OR_NULL(dma->rx_rb->buf)) {
+ dev_err(port->dev, "failed to allcoate RX DMA buffer\n");
+ rc = -ENOMEM;
+ goto out;
+ }
+
+ dma->tx_addr = dma_map_single(port->dev, dma->tx_rb->buf,
+ dma->tx_rbsz, DMA_TO_DEVICE);
+ if (dma_mapping_error(port->dev, dma->tx_addr)) {
+ dev_err(port->dev, "failed to map streaming TX DMA region\n");
+ rc = -ENOMEM;
+ goto free_dma_n_out;
+ }
+
+ dma->rx_addr = dma_map_single(port->dev, dma->rx_rb->buf,
+ dma->rx_rbsz, DMA_FROM_DEVICE);
+ if (dma_mapping_error(port->dev, dma->rx_addr)) {
+ dev_err(port->dev, "failed to map streaming RX DMA region\n");
+ rc = -ENOMEM;
+ goto free_dma_n_out;
+ }
+
+ rc = aspeed_udma_request_tx_chan(dma->ch, dma->tx_addr, dma->tx_rb,
+ dma->tx_rbsz, ast8250_dma_tx_complete,
+ port, dma->tx_tmout_dis);
+ if (rc) {
+ dev_err(port->dev, "failed to request DMA TX channel\n");
+ goto free_dma_n_out;
+ }
+
+ rc = aspeed_udma_request_rx_chan(dma->ch, dma->rx_addr, dma->rx_rb,
+ dma->rx_rbsz, ast8250_dma_rx_complete,
+ port, dma->rx_tmout_dis);
+ if (rc) {
+ dev_err(port->dev, "failed to request DMA RX channel\n");
+ goto free_dma_n_out;
+ }
+
+ ast8250_dma_pops_hook(port);
+
+ aspeed_udma_tx_chan_ctrl(dma->ch, ASPEED_UDMA_OP_ENABLE);
+ aspeed_udma_rx_chan_ctrl(dma->ch, ASPEED_UDMA_OP_ENABLE);
+ }
+
+ memset(&port->icount, 0, sizeof(port->icount));
+ return serial8250_do_startup(port);
+
+free_dma_n_out:
+ kfree(dma->rx_rb->buf);
+out:
+ return rc;
+}
+
+static void ast8250_shutdown(struct uart_port *port)
+{
+ int rc;
+ struct ast8250_data *data = port->private_data;
+ struct ast8250_udma *dma;
+
+ if (data->use_dma) {
+ dma = &data->dma;
+
+ aspeed_udma_tx_chan_ctrl(dma->ch, ASPEED_UDMA_OP_RESET);
+ aspeed_udma_rx_chan_ctrl(dma->ch, ASPEED_UDMA_OP_RESET);
+
+ aspeed_udma_tx_chan_ctrl(dma->ch, ASPEED_UDMA_OP_DISABLE);
+ aspeed_udma_rx_chan_ctrl(dma->ch, ASPEED_UDMA_OP_DISABLE);
+
+ rc = aspeed_udma_free_tx_chan(dma->ch);
+ if (rc)
+ dev_err(port->dev, "failed to free DMA TX channel, rc=%d\n", rc);
+
+ rc = aspeed_udma_free_rx_chan(dma->ch);
+ if (rc)
+ dev_err(port->dev, "failed to free DMA TX channel, rc=%d\n", rc);
+
+ dma_unmap_single(port->dev, dma->tx_addr,
+ dma->tx_rbsz, DMA_TO_DEVICE);
+ dma_unmap_single(port->dev, dma->rx_addr,
+ dma->rx_rbsz, DMA_FROM_DEVICE);
+
+ kfree(dma->rx_rb->buf);
+ }
+
+ if (data->is_vuart)
+ ast8250_vuart_set_host_tx_discard(data, true);
+
+ serial8250_do_shutdown(port);
+}
+
+static int __maybe_unused ast8250_suspend(struct device *dev)
+{
+ struct ast8250_data *data = dev_get_drvdata(dev);
+
+ serial8250_suspend_port(data->line);
+
+ return 0;
+}
+
+static int __maybe_unused ast8250_resume(struct device *dev)
+{
+ struct ast8250_data *data = dev_get_drvdata(dev);
+
+ serial8250_resume_port(data->line);
+
+ return 0;
+}
+
+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;
+ u32 irq;
+
+ data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+ if (data == NULL)
+ return -ENOMEM;
+
+ data->dma.rx_rb = devm_kzalloc(dev, sizeof(data->dma.rx_rb), GFP_KERNEL);
+ if (data->dma.rx_rb == NULL)
+ return -ENOMEM;
+
+ irq = platform_get_irq(pdev, 0);
+ if (irq < 0)
+ return 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);
+
+ data->is_vuart = of_property_read_bool(dev->of_node, "virtual");
+ if (data->is_vuart) {
+ rc = of_property_read_u32(dev->of_node, "port", &data->vuart.port);
+ if (rc) {
+ dev_err(dev, "failed to get VUART port address\n");
+ return -ENODEV;
+ }
+
+ rc = of_property_read_u32(dev->of_node, "sirq", &data->vuart.sirq);
+ if (rc) {
+ dev_err(dev, "failed to get VUART SIRQ number\n");
+ return -ENODEV;
+ }
+
+ rc = of_property_read_u32(dev->of_node, "sirq-polarity", &data->vuart.sirq_pol);
+ if (rc) {
+ dev_err(dev, "failed to get VUART SIRQ polarity\n");
+ return -ENODEV;
+ }
+
+ ast8250_vuart_init(data);
+ ast8250_vuart_set_host_tx_discard(data, true);
+ ast8250_vuart_set_enable(data, true);
+ }
+
+ data->use_dma = of_property_read_bool(dev->of_node, "dma-mode");
+ if (data->use_dma) {
+ rc = of_property_read_u32(dev->of_node, "dma-channel", &data->dma.ch);
+ if (rc) {
+ dev_err(dev, "failed to get DMA channel\n");
+ return -ENODEV;
+ }
+
+ data->dma.tx_tmout_dis = of_property_read_bool(dev->of_node,
+ "dma-tx-timeout-disable");
+ data->dma.rx_tmout_dis = of_property_read_bool(dev->of_node,
+ "dma-rx-timeout-disable");
+ }
+
+ spin_lock_init(&port->lock);
+ port->dev = dev;
+ port->type = PORT_16550A;
+ port->irq = 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;
+ uart.bugs |= UART_BUG_TXRACE;
+
+ data->line = serial8250_register_8250_port(&uart);
+ if (data->line < 0) {
+ dev_err(dev, "failed to register 8250 port\n");
+ return data->line;
+ }
+
+ pm_runtime_set_active(&pdev->dev);
+ pm_runtime_enable(&pdev->dev);
+
+ platform_set_drvdata(pdev, data);
+ return 0;
+}
+
+static int ast8250_remove(struct platform_device *pdev)
+{
+ struct ast8250_data *data = platform_get_drvdata(pdev);
+
+ if (data->is_vuart)
+ ast8250_vuart_set_enable(data, false);
+
+ serial8250_unregister_port(data->line);
+ return 0;
+}
+
+static const struct dev_pm_ops ast8250_pm_ops = {
+ SET_SYSTEM_SLEEP_PM_OPS(ast8250_suspend, ast8250_resume)
+};
+
+static const struct of_device_id ast8250_of_match[] = {
+ { .compatible = "aspeed,ast2600-uart" },
+};
+
+static struct platform_driver ast8250_platform_driver = {
+ .driver = {
+ .name = DEVICE_NAME,
+ .pm = &ast8250_pm_ops,
+ .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 at aspeedtech.com>");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Aspeed UART Driver");
diff --git a/drivers/tty/serial/8250/Kconfig b/drivers/tty/serial/8250/Kconfig
index b0f62345bc84..d8ecc261d8c4 100644
--- a/drivers/tty/serial/8250/Kconfig
+++ b/drivers/tty/serial/8250/Kconfig
@@ -538,6 +538,14 @@ config SERIAL_8250_BCM7271
including DMA support and high accuracy BAUD rates, say
Y to this option. If unsure, say N.
+config SERIAL_8250_ASPEED
+ tristate "Aspeed serial port support"
+ depends on SERIAL_8250 && ARCH_ASPEED
+ help
+ If you have a system using an Aspeed AST26xx SoCs and wish to
+ make use of its UARTs and VUARTs, which are 16550A compatible
+ and include DMA support, say Y to this option. If unsure, say N.
+
config SERIAL_OF_PLATFORM
tristate "Devicetree based probing for 8250 ports"
depends on SERIAL_8250 && OF
diff --git a/drivers/tty/serial/8250/Makefile b/drivers/tty/serial/8250/Makefile
index 1615bfdde2a0..7f05b7ed422b 100644
--- a/drivers/tty/serial/8250/Makefile
+++ b/drivers/tty/serial/8250/Makefile
@@ -42,6 +42,7 @@ obj-$(CONFIG_SERIAL_8250_PERICOM) += 8250_pericom.o
obj-$(CONFIG_SERIAL_8250_PXA) += 8250_pxa.o
obj-$(CONFIG_SERIAL_8250_TEGRA) += 8250_tegra.o
obj-$(CONFIG_SERIAL_8250_BCM7271) += 8250_bcm7271.o
+obj-$(CONFIG_SERIAL_8250_ASPEED) += 8250_aspeed.o
obj-$(CONFIG_SERIAL_OF_PLATFORM) += 8250_of.o
CFLAGS_8250_ingenic.o += -I$(srctree)/scripts/dtc/libfdt
--
2.25.1
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