[patch v4 0/5] *** AST2500 DMA UART driver ***

[patch v4 0/5] *** AST2500 DMA UART driver ***

[sudheer.v]

From: sudheer veliseti <sudheer.open@gmail.com>

Hi,

In this patchset v4,all the comments provided for patchset v3
are addressed.Also there is considerable
change in the code related to how the per port
uart structure is registerd with uart core.
so the patch [patch v4 1/5] considerably differs from [patch v3 1/5]

Thanks and Regards
Sudheer.V

changes in v4:
- since TX uart interrupt is being invoked by 8250 framework
  instead of expected TX DMA interrupt,registration of uart port is changed.
  per port uart structure registration is done directly now
  instead of going throgh 8250 framework.
  so there is considerable change in code against v3 patch
changes in v3:
- custom debugs replaced with pr_debug in 8250_ast2500_uart_dma.c
- change logs added in patches

sudheer veliseti (5):
  AST2500 DMA UART driver
  build configuration for AST2500 DMA UART driver
  DT nodes for AST2500 DMA UART driver
  defconfig and MAINTAINERS updated for AST2500 DMA UART driver
  Documentation: DT bindings AST2500 DMA UART driver

 .../bindings/serial/ast2500-dma-uart.txt      |   43 +
 MAINTAINERS                                   |   12 +
 arch/arm/boot/dts/aspeed-ast2500-evb.dts      |   21 +
 arch/arm/boot/dts/aspeed-g5.dtsi              |   71 +-
 arch/arm/configs/aspeed_g5_defconfig          |    1 +
 .../tty/serial/8250/8250_ast2500_uart_dma.c   | 1901 +++++++++++++++++
 drivers/tty/serial/8250/Kconfig               |   45 +-
 drivers/tty/serial/8250/Makefile              |    1 +
 8 files changed, 2090 insertions(+), 5 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/serial/ast2500-dma-uart.txt
 create mode 100644 drivers/tty/serial/8250/8250_ast2500_uart_dma.c

-- 
2.17.1

[patch v4 1/5] AST2500 DMA UART driver

[sudheer.v]

From: sudheer veliseti <sudheer.open@gmail.com>

UART driver for Aspeed's bmc chip AST2500

Design approch:
AST2500 has dedicated Uart DMA controller which has 12 sets of Tx and RX channels
connected to UART controller directly.
Since the DMA controller have dedicated buffers and registers,
there would be little benifit in adding DMA framework overhead.
So the software for DMA controller is included within the UART driver itself.

implementation details:
'struct ast_uart_port' is populated and registered with uart_core.
code is organised into two layers UART-layer and DMA-Layer,both of them are
in the same file.UART-layer requests Rx and Tx dma channels
and registers callbacks with DMA controller software Layer
Interrupt service routine for DMA controller is the crucial one for Handling all
the tx and rx data. ISRs installed for individual uarts are just dummy,and are helpful 
only to report any spurious interrupts in hardware.


Signed-off-by: sudheer veliseti <sudheer.open@gmail.com>
---

Changes from v3->v4:
- per port uart structures are registerd directly with uart core 
  Instead of registering through 8250 Frame work,
  ast_uart_port is registered using uart_add_one_port
-SDMA_RX_FIX macro replaced with CONFIG_AST_UART_DMA_RX_INTERRUPT
-ast_uart_sdma_isr : DMA interrupt handler code is improvised
-replaced pr_debug with ftrace wherever appropriate
-dev_err is used in all error return cases
-uart driver structure ast25xx_uart_reg is modified
-driver name changed to ast2500-uart-dma-drv
-rx_timer initialisation and callback fn modified

Changes from v2->v3:
-custom debug replaced by in kerenl dynamic debug: pr_debug 
-change-logs added 


.../tty/serial/8250/8250_ast2500_uart_dma.c   | 1901 +++++++++++++++++
 1 file changed, 1901 insertions(+)
 create mode 100644 drivers/tty/serial/8250/8250_ast2500_uart_dma.c

diff --git a/drivers/tty/serial/8250/8250_ast2500_uart_dma.c b/drivers/tty/serial/8250/8250_ast2500_uart_dma.c
new file mode 100644
index 000000000000..bc830d605372
--- /dev/null
+++ b/drivers/tty/serial/8250/8250_ast2500_uart_dma.c
@@ -0,0 +1,1901 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  DMA UART Driver for ASPEED BMC chip: AST2500
+ *
+ *  Copyright (C) 2019 sudheer Kumar veliseti, Aspeed technology Inc.
+ *  <open.sudheer@gmail.com>
+ *
+ */
+#include <linux/clk.h>
+#include <linux/dma-mapping.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/tty.h>
+#include <linux/tty_flip.h>
+#include "8250.h"
+
+#define SERIAL8250_CONSOLE NULL
+#define TTY_AST_MAJOR 204
+#define TTY_AST_MINOR 68
+
+#define DMA_BUFF_SIZE		0x1000
+#define SDMA_RX_BUFF_SIZE	0x10000
+#define PASS_LIMIT 256
+#define UART_DMA_NR CONFIG_AST_NR_DMA_UARTS
+#define AST_UART_SDMA_CH 12
+
+/* enum ast_uart_chan_op
+ * operation codes passed to the DMA code by the user, and also used
+ * to inform the current channel owner of any changes to the system state
+ */
+enum ast_uart_chan_op {
+	AST_UART_DMAOP_TRIGGER,
+	AST_UART_DMAOP_STOP,
+	AST_UART_DMAOP_PAUSE,
+};
+
+/* ast_uart_dma_cbfn: buffer callback routinei type */
+typedef void (*ast_uart_dma_cbfn)(void *dev_id, u16 len);
+
+struct ast_sdma_info {
+	u8 ch_no;
+	u8 direction;
+	u8 enable;
+	void *priv;
+	char *sdma_virt_addr;
+	dma_addr_t dma_phy_addr;
+	/* cdriver callbacks */
+	ast_uart_dma_cbfn callback_fn; /* buffer done callback */
+};
+
+struct ast_sdma_ch {
+	struct ast_sdma_info tx_dma_info[AST_UART_SDMA_CH];
+	struct ast_sdma_info rx_dma_info[AST_UART_SDMA_CH];
+};
+
+struct ast_sdma {
+	void __iomem *reg_base;
+	int dma_irq;
+	struct ast_sdma_ch *dma_ch;
+	struct regmap *map;
+};
+
+#define UART_TX_SDMA_EN		0x00
+#define UART_RX_SDMA_EN		0x04
+#define UART_SDMA_CONF		0x08 /* Misc, Buffer size  */
+#define UART_SDMA_TIMER		0x0C
+#define UART_TX_SDMA_REST	0x20
+#define UART_RX_SDMA_REST	0x24
+#define UART_TX_SDMA_IER	0x30
+#define UART_TX_SDMA_ISR	0x34
+#define UART_RX_SDMA_IER	0x38
+#define UART_RX_SDMA_ISR	0x3C
+#define UART_TX_R_POINT(x)	(0x40 + ((x) * 0x20))
+#define UART_TX_W_POINT(x)	(0x44 + ((x) * 0x20))
+#define UART_TX_SDMA_ADDR(x)	(0x48 + ((x) * 0x20))
+#define UART_RX_R_POINT(x)	(0x50 + ((x) * 0x20))
+#define UART_RX_W_POINT(x)	(0x54 + ((x) * 0x20))
+#define UART_RX_SDMA_ADDR(x)	(0x58 + ((x) * 0x20))
+#define SDMA_CH_EN(x)		BIT(x)
+
+#define SDMA_TX_BUFF_SIZE_MASK	(0x3)
+#define SDMA_SET_TX_BUFF_SIZE(x)(x)
+#define SDMA_BUFF_SIZE_1KB	(0x0)
+#define SDMA_BUFF_SIZE_4KB	(0x1)
+#define SDMA_BUFF_SIZE_16KB	(0x2)
+#define SDMA_BUFF_SIZE_64KB	(0x3)
+#define SDMA_RX_BUFF_SIZE_MASK	(0x3 << 2)
+#define SDMA_SET_RX_BUFF_SIZE(x)((x) << 2)
+#define SDMA_TIMEOUT_DIS	BIT(4)
+
+#define UART_SDMA11_INT		BIT(11)
+#define UART_SDMA10_INT		BIT(10)
+#define UART_SDMA9_INT		BIT(9)
+#define UART_SDMA8_INT		BIT(8)
+#define UART_SDMA7_INT		BIT(7)
+#define UART_SDMA6_INT		BIT(6)
+#define UART_SDMA5_INT		BIT(5)
+#define UART_SDMA4_INT		BIT(4)
+#define UART_SDMA3_INT		BIT(3)
+#define UART_SDMA2_INT		BIT(2)
+#define UART_SDMA1_INT		BIT(1)
+#define UART_SDMA0_INT		BIT(0)
+
+/*
+ * Configuration:
+ *   share_irqs - whether we pass IRQF_SHARED to request_irq().
+ *   This option is unsafe when used on edge-triggered interrupts.
+ */
+static unsigned int share_irqs = SERIAL8250_SHARE_IRQS;
+
+static unsigned int nr_uarts = CONFIG_AST_RUNTIME_DMA_UARTS;
+
+struct ast_uart_port {
+	struct uart_port port;
+	unsigned short capabilities; /* port capabilities */
+	unsigned short bugs;         /* port bugs */
+	unsigned int tx_loadsz;      /* transmit fifo load size */
+	unsigned char acr;
+	unsigned char ier;
+	unsigned char lcr;
+	unsigned char mcr;
+	unsigned char mcr_mask;  /* mask of user bits */
+	unsigned char mcr_force; /* mask of forced bits */
+	struct circ_buf rx_dma_buf;
+	struct circ_buf tx_dma_buf;
+	unsigned char dma_channel;
+	dma_addr_t dma_rx_addr; /* Mapped ADMA descr. table */
+	dma_addr_t dma_tx_addr; /* Mapped ADMA descr. table */
+#ifdef CONFIG_AST_UART_DMA_RX_INTERRUPT
+	struct tasklet_struct rx_tasklet;
+#else
+	struct timer_list rx_timer;
+	unsigned int workaround;
+#endif
+	struct tasklet_struct tx_tasklet;
+	spinlock_t lock;
+	int tx_done;
+	int tx_count;
+	struct platform_device *ast_uart_pdev;
+/*
+ * Some bits in registers are cleared on a read, so they must
+ * be saved whenever the register is read but the bits will not
+ * be immediately processed.
+ */
+#define LSR_SAVE_FLAGS UART_LSR_BRK_ERROR_BITS
+	unsigned char lsr_saved_flags;
+#define MSR_SAVE_FLAGS UART_MSR_ANY_DELTA
+	unsigned char msr_saved_flags;
+
+	/*
+	 * We provide a per-port pm hook.
+	 */
+	void (*pm)(struct uart_port *port, unsigned int state,
+						 unsigned int old);
+};
+
+static struct ast_uart_port ast_uart_ports[UART_DMA_NR];
+
+#define GET_DEV(ast_uart_port_priv_ptr)\
+		(ast_uart_port_priv_ptr->ast_uart_pdev->dev)
+
+static inline struct ast_uart_port *
+to_ast_dma_uart_port(struct uart_port *uart) {
+	return container_of(uart, struct ast_uart_port, port);
+}
+
+struct irq_info {
+	spinlock_t lock;
+	struct ast_uart_port *up;
+};
+
+static struct irq_info ast_uart_irq[1];
+static DEFINE_MUTEX(ast_uart_mutex);
+
+/*
+ * Here we define the default xmit fifo size used for each type of UART.
+ */
+static const struct serial8250_config uart_config[] = {
+	[PORT_UNKNOWN] = {
+		.name		= "unknown",
+		.fifo_size	= 1,
+		.tx_loadsz	= 1,
+	},
+	[PORT_8250] = {
+		.name		= "8250",
+		.fifo_size	= 1,
+		.tx_loadsz	= 1,
+	},
+	[PORT_16450] = {
+		.name		= "16450",
+		.fifo_size	= 1,
+		.tx_loadsz	= 1,
+	},
+	[PORT_16550] = {
+		.name		= "16550",
+		.fifo_size	= 1,
+		.tx_loadsz	= 1,
+	},
+	[PORT_16550A] = {
+		.name		= "16550A",
+		.fifo_size	= 16,
+		.tx_loadsz	= 16,
+		.fcr		= UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10
+							| UART_FCR_DMA_SELECT,
+		.flags		= UART_CAP_FIFO,
+	},
+};
+
+#define map_8250_reg_offset(up, offset)  ((offset) << (up->port.regshift))
+
+
+
+// SDMA - software Layer : ast-uart-sdma.c
+static inline void ast_uart_sdma_write(struct ast_sdma *sdma,
+						u32 val, u32 reg)
+{
+	trace_printk("uart dma-write : val: %x, reg: %x\n", val, reg);
+	writel(val, sdma->reg_base + reg);
+}
+
+static inline u32 ast_uart_sdma_read(struct ast_sdma *sdma, u32 reg)
+{
+	return readl(sdma->reg_base + reg);
+}
+
+struct ast_sdma ast_uart_sdma;
+
+int ast_uart_tx_sdma_enqueue(u8 ch, dma_addr_t tx_buff)
+{
+	unsigned long flags;
+	struct ast_sdma *sdma = &ast_uart_sdma;
+
+	trace_printk("ch = %d, tx buff = %x\n", ch, tx_buff);
+	local_irq_save(flags);
+	ast_uart_sdma_write(sdma, tx_buff, UART_TX_SDMA_ADDR(ch));
+	local_irq_restore(flags);
+
+	return 0;
+}
+
+void ast_uart_set_sdma_time_out(u16 val)
+{
+	struct ast_sdma *sdma = &ast_uart_sdma;
+
+	ast_uart_sdma_write(sdma, val, UART_SDMA_TIMER);
+}
+
+int ast_uart_rx_sdma_ctrl(u8 ch, enum ast_uart_chan_op op)
+{
+	unsigned long flags;
+	struct ast_sdma *sdma = &ast_uart_sdma;
+	struct ast_sdma_info *dma_ch = &(sdma->dma_ch->rx_dma_info[ch]);
+
+	local_irq_save(flags);
+	trace_printk("ch=%d op=%d\n", ch, op);
+	switch (op) {
+	case AST_UART_DMAOP_TRIGGER:
+		dma_ch->enable = 1;
+#ifndef CONFIG_AST_UART_DMA_RX_INTERRUPT
+		ast_uart_set_sdma_time_out(0xffff);
+#endif
+		// set enable
+		ast_uart_sdma_write(sdma,
+			ast_uart_sdma_read(sdma, UART_RX_SDMA_EN) | (0x1 << ch),
+			UART_RX_SDMA_EN);
+		break;
+	case AST_UART_DMAOP_STOP:
+		// disable engine
+		dma_ch->enable = 0;
+		ast_uart_sdma_write(sdma,
+			ast_uart_sdma_read(sdma, UART_RX_SDMA_EN)
+			& ~(0x1 << ch), UART_RX_SDMA_EN);
+		// set reset
+		ast_uart_sdma_write(sdma,
+			ast_uart_sdma_read(sdma, UART_RX_SDMA_REST) |
+				  (0x1 << ch), UART_RX_SDMA_REST);
+		ast_uart_sdma_write(sdma,
+			ast_uart_sdma_read(sdma, UART_RX_SDMA_REST) &
+				  ~(0x1 << ch),	UART_RX_SDMA_REST);
+
+		ast_uart_sdma_write(sdma, 0, UART_RX_R_POINT(ch));
+		ast_uart_sdma_write(sdma,
+			dma_ch->dma_phy_addr, UART_RX_SDMA_ADDR(ch));
+		break;
+	case AST_UART_DMAOP_PAUSE:
+		// disable engine
+		dma_ch->enable = 0;
+		ast_uart_sdma_write(sdma,
+			ast_uart_sdma_read(sdma, UART_RX_SDMA_EN) &
+				  ~(0x1 << ch),	UART_RX_SDMA_EN);
+		break;
+	}
+
+	local_irq_restore(flags);
+	return 0;
+}
+
+int ast_uart_tx_sdma_ctrl(u8 ch, enum ast_uart_chan_op op)
+{
+	unsigned long flags;
+	struct ast_sdma *sdma = &ast_uart_sdma;
+	struct ast_sdma_info *dma_ch = &(sdma->dma_ch->tx_dma_info[ch]);
+
+	trace_printk("ch=%d op=%d\n", ch, op);
+	local_irq_save(flags);
+	switch (op) {
+	case AST_UART_DMAOP_TRIGGER:
+		dma_ch->enable = 1;
+		// set enable
+		ast_uart_sdma_write(sdma,
+			ast_uart_sdma_read(sdma, UART_TX_SDMA_EN) | (0x1 << ch),
+			UART_TX_SDMA_EN);
+		break;
+	case AST_UART_DMAOP_STOP:
+		dma_ch->enable = 0;
+		// disable engine
+		ast_uart_sdma_write(sdma,
+			ast_uart_sdma_read(sdma, UART_TX_SDMA_EN)
+			& ~(0x1 << ch), UART_TX_SDMA_EN);
+		// set reset
+		ast_uart_sdma_write(sdma,
+			ast_uart_sdma_read(sdma, UART_TX_SDMA_REST)
+			| (0x1 << ch), UART_TX_SDMA_REST);
+		ast_uart_sdma_write(sdma,
+			ast_uart_sdma_read(sdma, UART_TX_SDMA_REST)
+			& ~(0x1 << ch),	UART_TX_SDMA_REST);
+
+		ast_uart_sdma_write(sdma, 0, UART_TX_W_POINT(ch));
+		break;
+	case AST_UART_DMAOP_PAUSE:
+		dma_ch->enable = 0;
+		// disable engine
+		ast_uart_sdma_write(sdma,
+			ast_uart_sdma_read(sdma, UART_TX_SDMA_EN)
+			& ~(0x1 << ch),	UART_TX_SDMA_EN);
+	}
+
+	local_irq_restore(flags);
+	return 0;
+}
+
+u32 ast_uart_get_tx_sdma_pt(u8 ch)
+{
+	struct ast_sdma *sdma = &ast_uart_sdma;
+
+	return ast_uart_sdma_read(sdma, UART_TX_R_POINT(ch));
+}
+
+int ast_uart_tx_sdma_update(u8 ch, u16 point)
+{
+	unsigned long flags;
+	struct ast_sdma *sdma = &ast_uart_sdma;
+
+	trace_printk("TX DMA CTRL [ch %d] point %d\n", ch, point);
+	local_irq_save(flags);
+	ast_uart_sdma_write(sdma, point, UART_TX_W_POINT(ch));
+	local_irq_restore(flags);
+	return 0;
+}
+
+int ast_uart_tx_sdma_request(u8 ch, ast_uart_dma_cbfn rtn, void *id)
+{
+	unsigned long flags;
+	struct ast_sdma *sdma = &ast_uart_sdma;
+	struct ast_sdma_info *dma_ch = &(sdma->dma_ch->tx_dma_info[ch]);
+
+	trace_printk("TX DMA REQUEST ch = %d\n", ch);
+	local_irq_save(flags);
+	if (dma_ch->enable) {
+		local_irq_restore(flags);
+		return -EBUSY;
+	}
+	dma_ch->priv = id;
+	dma_ch->callback_fn = rtn;
+
+	// DMA IRQ En
+	ast_uart_sdma_write(sdma,
+		      ast_uart_sdma_read(sdma, UART_TX_SDMA_IER) | (1 << ch),
+		      UART_TX_SDMA_IER);
+
+	local_irq_restore(flags);
+
+	return 0;
+}
+
+int ast_uart_rx_sdma_update(u8 ch, u16 point)
+{
+	unsigned long flags;
+	struct ast_sdma *sdma = &ast_uart_sdma;
+
+	trace_printk("RX DMA CTRL [ch %d] point %x\n", ch, point);
+	local_irq_save(flags);
+	ast_uart_sdma_write(sdma, point, UART_RX_R_POINT(ch));
+	local_irq_restore(flags);
+	return 0;
+}
+
+#ifdef CONFIG_AST_UART_DMA_RX_INTERRUPT
+char *ast_uart_rx_sdma_request(u8 ch, ast_uart_dma_cbfn rtn, void *id)
+{
+	unsigned long flags;
+	struct ast_sdma *sdma = &ast_uart_sdma;
+	struct ast_sdma_info *dma_ch = &(sdma->dma_ch->rx_dma_info[ch]);
+
+	trace_printk("RX DMA REQUEST ch = %d\n", ch);
+	local_irq_save(flags);
+
+	if (dma_ch->enable) {
+		local_irq_restore(flags);
+		return 0;
+	}
+	dma_ch->priv = id;
+	dma_ch->callback_fn = rtn;
+	// DMA IRQ En
+	ast_uart_sdma_write(sdma,
+		      ast_uart_sdma_read(sdma, UART_RX_SDMA_IER) | (1 << ch),
+		      UART_RX_SDMA_IER);
+
+	local_irq_restore(flags);
+
+	return dma_ch->sdma_virt_addr;
+}
+
+#else
+char *ast_uart_rx_sdma_request(u8 ch, void *id)
+{
+	unsigned long flags;
+	struct ast_sdma *sdma = &ast_uart_sdma;
+	struct ast_sdma_info *dma_ch = &(sdma->dma_ch->rx_dma_info[ch]);
+
+	trace_printk("RX DMA REQUEST ch = %d\n", ch);
+
+	local_irq_save(flags);
+
+	if (dma_ch->enable) {
+		local_irq_restore(flags);
+		return ERR_PTR(-EBUSY);
+	}
+	dma_ch->priv = id;
+
+	local_irq_restore(flags);
+	return dma_ch->sdma_virt_addr;
+}
+#endif
+
+u16 ast_uart_get_rx_sdma_pt(u8 ch)
+{
+	struct ast_sdma *sdma = &ast_uart_sdma;
+
+	return ast_uart_sdma_read(sdma, UART_RX_W_POINT(ch));
+}
+
+static inline void ast_sdma_bufffdone(struct ast_sdma_info *sdma_ch)
+{
+	u32 len;
+	struct ast_sdma *sdma = &ast_uart_sdma;
+
+	if (sdma_ch->enable == 0) {
+		pr_debug("sdma Please check ch_no %x %s!!!!!\n",
+			sdma_ch->ch_no, sdma_ch->direction ? "TX" : "RX");
+		if (sdma_ch->direction) {
+			ast_uart_sdma_write(sdma,
+				ast_uart_sdma_read(sdma, UART_TX_SDMA_EN)
+				& ~(0x1 << sdma_ch->ch_no), UART_TX_SDMA_EN);
+		} else {
+			ast_uart_sdma_write(sdma,
+				ast_uart_sdma_read(sdma, UART_RX_SDMA_EN) &
+				~(0x1 << sdma_ch->ch_no), UART_RX_SDMA_EN);
+			ast_uart_rx_sdma_update(sdma_ch->ch_no,
+				ast_uart_get_rx_sdma_pt(sdma_ch->ch_no));
+			trace_printk("OFFSET : UART_RX_SDMA_EN = %x\n ",
+				ast_uart_sdma_read(sdma, UART_RX_SDMA_EN));
+		}
+		return;
+	}
+
+	if (sdma_ch->direction) {
+		len = ast_uart_sdma_read(sdma, UART_TX_R_POINT(sdma_ch->ch_no));
+		trace_printk("tx rp %x , wp %x\n",
+		ast_uart_sdma_read(sdma, UART_TX_R_POINT(sdma_ch->ch_no)),
+		ast_uart_sdma_read(sdma, UART_TX_W_POINT(sdma_ch->ch_no))
+		);
+	} else {
+		trace_printk("rx rp %x , wp %x\n",
+		ast_uart_sdma_read(sdma, UART_RX_R_POINT(sdma_ch->ch_no)),
+		ast_uart_sdma_read(sdma, UART_RX_W_POINT(sdma_ch->ch_no))
+		);
+		len = ast_uart_sdma_read(sdma, UART_RX_W_POINT(sdma_ch->ch_no));
+	}
+
+	trace_printk("<dma dwn>: ch[%d] : %s ,len : %d\n", sdma_ch->ch_no,
+				sdma_ch->direction ? "tx" : "rx", len);
+
+	if (sdma_ch->callback_fn != NULL)
+		(sdma_ch->callback_fn)(sdma_ch->priv, len);
+}
+
+static irqreturn_t ast_uart_sdma_isr(int irq, void *dev_id)
+{
+	struct ast_sdma *sdma = (struct ast_sdma *)dev_id;
+	int sdma_int_num = 0;
+	u32 tx_sts = ast_uart_sdma_read(sdma, UART_TX_SDMA_ISR);
+	u32 rx_sts = ast_uart_sdma_read(sdma, UART_RX_SDMA_ISR);
+
+	trace_printk("tx sts : %x, rx sts : %x\n", tx_sts, rx_sts);
+	if ((tx_sts == 0) && (rx_sts == 0)) {
+		pr_err("SDMA IRQ ERROR !!!\n");
+		return IRQ_HANDLED;
+	}
+
+	while ((sdma_int_num = ffs(rx_sts)))  {
+		ast_uart_sdma_write(sdma,
+			BIT(sdma_int_num-1), UART_RX_SDMA_ISR);
+		ast_sdma_bufffdone(
+			&(sdma->dma_ch->rx_dma_info[sdma_int_num-1]));
+		rx_sts = rx_sts & (~BIT(sdma_int_num-1));
+	}
+	while ((sdma_int_num = ffs(tx_sts)))  {
+		ast_uart_sdma_write(sdma,
+			BIT(sdma_int_num-1), UART_TX_SDMA_ISR);
+		ast_sdma_bufffdone(
+			&(sdma->dma_ch->tx_dma_info[sdma_int_num-1]));
+		tx_sts = tx_sts & (~BIT(sdma_int_num-1));
+	}
+	return IRQ_HANDLED;
+}
+
+static int ast_uart_sdma_probe(void)
+{
+	int i;
+	struct device_node *node;
+	int ret;
+	struct ast_sdma *sdma = &ast_uart_sdma;
+	char *rx_dma_virt_addr;
+	dma_addr_t rx_dma_phy_addr;
+
+	sdma->dma_ch = kzalloc(sizeof(struct ast_sdma_ch), GFP_KERNEL);
+	if (!sdma->dma_ch)
+		return -ENOMEM;
+
+	// sdma memory mapping
+	node = of_find_compatible_node(NULL, NULL, "aspeed,ast-uart-sdma");
+	if (!node)
+		return -ENODEV;
+
+	sdma->reg_base = of_iomap(node, 0);
+	if (IS_ERR(sdma->reg_base))
+		return PTR_ERR(sdma->map);
+	rx_dma_virt_addr = dma_alloc_coherent(NULL,
+				SDMA_RX_BUFF_SIZE * AST_UART_SDMA_CH,
+					&rx_dma_phy_addr, GFP_KERNEL);
+
+	if (!rx_dma_virt_addr) {
+		pr_err("rx_dma_virt_addr Err:dma alloc Failed\n");
+		return -ENOMEM;
+	}
+	for (i = 0; i < AST_UART_SDMA_CH; i++) {
+		// TX ------------------------
+		sdma->dma_ch->tx_dma_info[i].enable = 0;
+		sdma->dma_ch->tx_dma_info[i].ch_no = i;
+		sdma->dma_ch->tx_dma_info[i].direction = 1;
+		ast_uart_sdma_write(sdma, 0, UART_TX_W_POINT(i));
+		// RX ------------------------
+		sdma->dma_ch->rx_dma_info[i].enable = 0;
+		sdma->dma_ch->rx_dma_info[i].ch_no = i;
+		sdma->dma_ch->rx_dma_info[i].direction = 0;
+		sdma->dma_ch->rx_dma_info[i].sdma_virt_addr =
+		rx_dma_virt_addr + (SDMA_RX_BUFF_SIZE * i);
+		sdma->dma_ch->rx_dma_info[i].dma_phy_addr =
+		rx_dma_phy_addr + (SDMA_RX_BUFF_SIZE * i);
+		ast_uart_sdma_write(sdma,
+			sdma->dma_ch->rx_dma_info[i].dma_phy_addr,
+			UART_RX_SDMA_ADDR(i));
+		ast_uart_sdma_write(sdma, 0, UART_RX_R_POINT(i));
+	}
+
+	ast_uart_sdma_write(sdma, 0xffffffff, UART_TX_SDMA_REST);
+	ast_uart_sdma_write(sdma, 0x0, UART_TX_SDMA_REST);
+
+	ast_uart_sdma_write(sdma, 0xffffffff, UART_RX_SDMA_REST);
+	ast_uart_sdma_write(sdma, 0x0, UART_RX_SDMA_REST);
+
+	ast_uart_sdma_write(sdma, 0, UART_TX_SDMA_EN);
+	ast_uart_sdma_write(sdma, 0, UART_RX_SDMA_EN);
+
+#ifdef CONFIG_AST_UART_DMA_RX_INTERRUPT
+	ast_uart_sdma_write(sdma, 0x200, UART_SDMA_TIMER);
+#else
+	ast_uart_sdma_write(sdma, 0xffff, UART_SDMA_TIMER);
+#endif
+
+	// TX
+	ast_uart_sdma_write(sdma, 0xfff, UART_TX_SDMA_ISR);
+	ast_uart_sdma_write(sdma, 0, UART_TX_SDMA_IER);
+
+	// RX
+	ast_uart_sdma_write(sdma, 0xfff, UART_RX_SDMA_ISR);
+	ast_uart_sdma_write(sdma, 0, UART_RX_SDMA_IER);
+
+	sdma->dma_irq = of_irq_get(node, 0);
+	ret = request_irq(sdma->dma_irq, ast_uart_sdma_isr, 0,
+						"sdma-intr", sdma);
+	if (ret) {
+		pr_err("Unable to get UART SDMA IRQ %x\n", ret);
+		return -ENODEV;
+	}
+
+	ast_uart_sdma_write(sdma, SDMA_SET_TX_BUFF_SIZE(SDMA_BUFF_SIZE_4KB) |
+				SDMA_SET_RX_BUFF_SIZE(SDMA_BUFF_SIZE_64KB),
+		      UART_SDMA_CONF);
+	return 0;
+}
+// END of SDMA Layer
+
+
+// UART Driver Layer
+static unsigned int ast_serial_in(struct ast_uart_port *up, int offset)
+{
+	offset = map_8250_reg_offset(up, offset);
+	return readb(up->port.membase + offset);
+}
+
+static void ast_serial_out(struct ast_uart_port *up, int offset, int value)
+{
+	/* Save the offset before it's remapped */
+	offset = map_8250_reg_offset(up, offset);
+	writeb(value, up->port.membase + offset);
+}
+
+#define serial_inp(up, offset) ast_serial_in(up, offset)
+#define serial_outp(up, offset, value) ast_serial_out(up, offset, value)
+
+/* Uart divisor latch read */
+static inline int _serial_dl_read(struct ast_uart_port *up)
+{
+	return serial_inp(up, UART_DLL) | serial_inp(up, UART_DLM) << 8;
+}
+
+/* Uart divisor latch write */
+static inline void _serial_dl_write(struct ast_uart_port *up, int value)
+{
+	serial_outp(up, UART_DLL, value & 0xff);
+	serial_outp(up, UART_DLM, value >> 8 & 0xff);
+}
+
+#define serial_dl_read(up) _serial_dl_read(up)
+#define serial_dl_write(up, value) _serial_dl_write(up, value)
+
+static void ast_uart_tx_sdma_tasklet_func(unsigned long data)
+{
+	struct ast_uart_port *up = to_ast_dma_uart_port(
+					(struct uart_port *)data);
+	struct circ_buf *xmit = &up->port.state->xmit;
+	u32 tx_pt;
+
+	spin_lock(&up->port.lock);
+
+	up->tx_count = CIRC_CNT(xmit->head, xmit->tail, UART_XMIT_SIZE);
+	dma_sync_single_for_device(up->port.dev, up->dma_tx_addr,
+					UART_XMIT_SIZE, DMA_TO_DEVICE);
+	tx_pt = ast_uart_get_tx_sdma_pt(up->dma_channel);
+
+	if (tx_pt > xmit->head)	{
+		if ((tx_pt & 0xfffc) == 0)
+			ast_uart_tx_sdma_update(up->dma_channel, 0xffff);
+		else
+			ast_uart_tx_sdma_update(up->dma_channel, 0);
+	} else {
+		ast_uart_tx_sdma_update(up->dma_channel, xmit->head);
+	}
+	ast_uart_tx_sdma_update(up->dma_channel, xmit->head);
+	spin_unlock(&up->port.lock);
+}
+
+static void ast_uart_tx_buffdone(void *dev_id, u16 len)
+{
+	struct ast_uart_port *up = (struct ast_uart_port *)dev_id;
+	struct circ_buf *xmit = &up->port.state->xmit;
+
+	trace_printk("line[%d] : tx len = % d\n", up->port.line, len);
+	spin_lock(&up->port.lock);
+	xmit->tail = len;
+	trace_printk(" line[%d], xmit->head = %d, xmit->tail = % d\n",
+			up->port.line, xmit->head, xmit->tail);
+
+	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		uart_write_wakeup(&up->port);
+
+	if (xmit->head != xmit->tail)
+		tasklet_schedule(&up->tx_tasklet);
+
+	spin_unlock(&up->port.lock);
+}
+
+#ifdef CONFIG_AST_UART_DMA_RX_INTERRUPT
+static void ast_uart_rx_sdma_tasklet_func(unsigned long data)
+{
+	struct ast_uart_port *up = to_ast_dma_uart_port(
+					(struct uart_port *)data);
+	struct tty_port *port = &up->port.state->port;
+	struct circ_buf *rx_ring = &up->rx_dma_buf;
+
+	int count;
+	int copy = 0;
+
+	trace_printk("line[%d], rx_ring->head = % d, rx_ring->tail = % d\n",
+			 up->port.line, rx_ring->head, rx_ring->tail);
+
+	spin_lock(&up->port.lock);
+	if (rx_ring->head > rx_ring->tail) {
+		count = rx_ring->head - rx_ring->tail;
+		copy = tty_insert_flip_string(port,
+				rx_ring->buf + rx_ring->tail, count);
+	} else if (rx_ring->head < rx_ring->tail) {
+		count = SDMA_RX_BUFF_SIZE - rx_ring->tail;
+		copy = tty_insert_flip_string(port,
+					rx_ring->buf + rx_ring->tail, count);
+	} else {
+		count = 0;
+	}
+
+	if (copy != count)
+		dev_err(&GET_DEV(up), "RxData copy to tty layer failed\n");
+	if (count) {
+		rx_ring->tail += count;
+		rx_ring->tail &= (SDMA_RX_BUFF_SIZE - 1);
+		up->port.icount.rx += count;
+		tty_flip_buffer_push(port);
+		ast_uart_rx_sdma_update(up->dma_channel, rx_ring->tail);
+	}
+	spin_unlock(&up->port.lock);
+}
+
+static void ast_uart_rx_buffdone(void *dev_id, u16 len)
+{
+	struct ast_uart_port *up = (struct ast_uart_port *)dev_id;
+	struct circ_buf *rx_ring = &up->rx_dma_buf;
+
+	trace_printk("line[%d], head = %d,len:%d\n",
+			 up->port.line, up->rx_dma_buf.head, len);
+
+	spin_lock(&up->port.lock);
+	rx_ring->head = len;
+	spin_unlock(&up->port.lock);
+	tasklet_schedule(&up->rx_tasklet);
+}
+
+#else
+static void ast_uart_rx_timer_func(struct timer_list *t)
+{
+	struct ast_uart_port *up = from_timer(up, t, rx_timer);
+	struct tty_port *port = &up->port.state->port;
+	struct circ_buf *rx_ring = &up->rx_dma_buf;
+	int count, copy = 0;
+
+	trace_printk("line[%d], rx_ring->head = % d, rx_ring->tail = % d\n",
+				up->port.line, rx_ring->head, rx_ring->tail);
+
+	rx_ring->head = ast_uart_get_rx_sdma_pt(up->dma_channel);
+
+	del_timer(&up->rx_timer);
+
+	if (rx_ring->head > rx_ring->tail) {
+		ast_uart_set_sdma_time_out(0xffff);
+		count = rx_ring->head - rx_ring->tail;
+		copy = tty_insert_flip_string(port,
+				 rx_ring->buf + rx_ring->tail, count);
+	} else if (rx_ring->head < rx_ring->tail) {
+		ast_uart_set_sdma_time_out(0xffff);
+		count = SDMA_RX_BUFF_SIZE - rx_ring->tail;
+		copy = tty_insert_flip_string(port,
+				 rx_ring->buf + rx_ring->tail, count);
+	} else {
+		count = 0;
+		trace_printk("@@--%s-- ch = 0x%x\n", __func__, ch);
+	}
+
+	if (copy != count)
+		dev_err(&GET_DEV(up), "RxData copy to tty layer failed\n");
+
+	if (count) {
+		rx_ring->tail += count;
+		rx_ring->tail &= (SDMA_RX_BUFF_SIZE - 1);
+	}
+	if (count) {
+		trace_printk("\n count = % d\n", count);
+		up->port.icount.rx += count;
+		spin_lock(&up->port.lock);
+		tty_flip_buffer_push(port);
+		spin_unlock(&up->port.lock);
+		trace_printk("update rx_ring->tail % x\n", rx_ring->tail);
+		ast_uart_rx_sdma_update(up->dma_channel, rx_ring->tail);
+		up->workaround = 1;
+	} else {
+		if (up->workaround) {
+			up->workaround++;
+			if (up->workaround > 1)
+				ast_uart_set_sdma_time_out(0);
+			else
+				ast_uart_set_sdma_time_out(0xffff);
+		}
+	}
+	add_timer(&up->rx_timer);
+}
+#endif
+
+/*
+ * FIFO support.
+ */
+inline void ast25xx_uart_clear_fifos(struct ast_uart_port *p)
+{
+	serial_outp(p, UART_FCR, UART_FCR_ENABLE_FIFO);
+	serial_outp(p, UART_FCR,
+	      UART_FCR_ENABLE_FIFO | UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT);
+	serial_outp(p, UART_FCR, 0);
+}
+
+/*
+ * This routine is called by rs_init() to initialize a specific serial
+ * port.
+ */
+static void autoconfig(struct ast_uart_port *up)
+{
+	unsigned long flags;
+
+	trace_printk("line[%d]\n", up->port.line);
+	if (!up->port.iobase && !up->port.mapbase && !up->port.membase)
+		return;
+
+	trace_printk("ttyDMA%d : autoconf (0x%04lx, 0x%p) : ", up->port.line,
+		 up->port.iobase, up->port.membase);
+
+	spin_lock_irqsave(&up->port.lock, flags);
+
+	up->capabilities = 0;
+	up->bugs = 0;
+
+	up->port.type = PORT_16550A;
+	up->capabilities |= UART_CAP_FIFO;
+
+	up->port.fifosize = uart_config[up->port.type].fifo_size;
+	up->capabilities = uart_config[up->port.type].flags;
+	up->tx_loadsz = uart_config[up->port.type].tx_loadsz;
+
+	if (up->port.type == PORT_UNKNOWN)
+		goto out;
+
+	/*
+	 * Reset the UART.
+	 */
+	ast25xx_uart_clear_fifos(up);
+	ast_serial_in(up, UART_RX);
+	serial_outp(up, UART_IER, 0);
+
+out:
+	spin_unlock_irqrestore(&up->port.lock, flags);
+	trace_printk("type=%s\n", uart_config[up->port.type].name);
+}
+
+static inline void __stop_tx(struct ast_uart_port *p)
+{
+	if (p->ier & UART_IER_THRI) {
+		p->ier &= ~UART_IER_THRI;
+		ast_serial_out(p, UART_IER, p->ier);
+	}
+}
+
+void ast25xx_uart_stop_tx(struct uart_port *port)
+{
+	struct ast_uart_port *up = to_ast_dma_uart_port(port);
+
+	trace_printk("line[%d]\n", up->port.line);
+	__stop_tx(up);
+}
+
+static void transmit_chars(struct ast_uart_port *up);
+
+static void ast25xx_uart_start_tx(struct uart_port *port)
+{
+	struct ast_uart_port *up = to_ast_dma_uart_port(port);
+
+	trace_printk("line[%d]\n", port->line);
+	tasklet_schedule(&up->tx_tasklet);
+}
+
+static void ast25xx_uart_stop_rx(struct uart_port *port)
+{
+	struct ast_uart_port *up = to_ast_dma_uart_port(port);
+
+	trace_printk("line[%d]\n", port->line);
+	up->ier &= ~UART_IER_RLSI;
+	up->port.read_status_mask &= ~UART_LSR_DR;
+	ast_serial_out(up, UART_IER, up->ier);
+}
+
+static void ast25xx_uart_enable_ms(struct uart_port *port)
+{
+	struct ast_uart_port *up = to_ast_dma_uart_port(port);
+
+	trace_printk("line[%d]\n", port->line);
+	up->ier |= UART_IER_MSI;
+	ast_serial_out(up, UART_IER, up->ier);
+}
+
+static void transmit_chars(struct ast_uart_port *up)
+{
+	struct circ_buf *xmit = &up->port.state->xmit;
+	int count;
+
+	if (up->port.x_char) {
+		serial_outp(up, UART_TX, up->port.x_char);
+		up->port.icount.tx++;
+		up->port.x_char = 0;
+		return;
+	}
+	if (uart_tx_stopped(&up->port)) {
+		ast25xx_uart_stop_tx(&up->port);
+		return;
+	}
+	if (uart_circ_empty(xmit)) {
+		__stop_tx(up);
+		return;
+	}
+
+	count = up->tx_loadsz;
+	do {
+		ast_serial_out(up, UART_TX, xmit->buf[xmit->tail]);
+		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
+		up->port.icount.tx++;
+		if (uart_circ_empty(xmit))
+			break;
+	} while (--count > 0);
+
+	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		uart_write_wakeup(&up->port);
+
+	if (uart_circ_empty(xmit))
+		__stop_tx(up);
+}
+
+static unsigned int check_modem_status(struct ast_uart_port *up)
+{
+	unsigned int status = ast_serial_in(up, UART_MSR);
+
+	trace_printk("line[%d]\n", up->port.line);
+	status |= up->msr_saved_flags;
+	up->msr_saved_flags = 0;
+	if (status & UART_MSR_ANY_DELTA && up->ier & UART_IER_MSI
+					&& up->port.state != NULL) {
+		if (status & UART_MSR_TERI)
+			up->port.icount.rng++;
+		if (status & UART_MSR_DDSR)
+			up->port.icount.dsr++;
+		if (status & UART_MSR_DDCD)
+			uart_handle_dcd_change(&up->port,
+					status & UART_MSR_DCD);
+		if (status & UART_MSR_DCTS)
+			uart_handle_cts_change(&up->port,
+					status & UART_MSR_CTS);
+
+		wake_up_interruptible(&up->port.state->port.delta_msr_wait);
+	}
+
+	return status;
+}
+
+/*
+ * handles the interrupt from one port.
+ */
+static inline void ast25xx_uart_handle_port(struct ast_uart_port *up)
+{
+	unsigned int status;
+	unsigned long flags;
+
+	spin_lock_irqsave(&up->port.lock, flags);
+
+	status = serial_inp(up, UART_LSR);
+
+	trace_printk("status = %x\n", status);
+
+	check_modem_status(up);
+	if (status & UART_LSR_THRE)
+		transmit_chars(up);
+
+	spin_unlock_irqrestore(&up->port.lock, flags);
+}
+
+/*
+ * serial driver's interrupt routine.
+ */
+static irqreturn_t ast_uart_interrupt(int irq, void *dev_id)
+{
+	struct irq_info *i = dev_id;
+	int pass_counter = 0, handled = 0, end = 0;
+
+	trace_printk("(%d)-", irq);
+	spin_lock(&i->lock);
+
+	do {
+		struct ast_uart_port *up;
+		unsigned int iir;
+
+		up = (struct ast_uart_port *)(i->up);
+
+		iir = ast_serial_in(up, UART_IIR);
+		if (!(iir & UART_IIR_NO_INT)) {
+			ast25xx_uart_handle_port(up);
+			handled = 1;
+
+		} else
+			end = 1;
+
+		if (pass_counter++ > PASS_LIMIT) {
+			pr_err("ast-uart-dma:too much work for irq%d\n", irq);
+			break;
+		}
+	} while (end);
+
+	spin_unlock(&i->lock);
+
+	trace_printk("-(%d)\n", irq);
+
+	return IRQ_RETVAL(handled);
+}
+
+static unsigned int ast25xx_uart_tx_empty(struct uart_port *port)
+{
+	struct ast_uart_port *up = to_ast_dma_uart_port(port);
+	unsigned long flags;
+	unsigned int lsr;
+
+	trace_printk("line[%d]\n", up->port.line);
+
+	spin_lock_irqsave(&up->port.lock, flags);
+	lsr = ast_serial_in(up, UART_LSR);
+	up->lsr_saved_flags |= lsr & LSR_SAVE_FLAGS;
+	spin_unlock_irqrestore(&up->port.lock, flags);
+
+	return lsr & UART_LSR_TEMT ? TIOCSER_TEMT : 0;
+}
+
+static unsigned int ast25xx_uart_get_mctrl(struct uart_port *port)
+{
+	struct ast_uart_port *up = to_ast_dma_uart_port(port);
+	unsigned int status;
+	unsigned int ret;
+
+	status = check_modem_status(up);
+
+	ret = 0;
+	if (status & UART_MSR_DCD)
+		ret |= TIOCM_CAR;
+	if (status & UART_MSR_RI)
+		ret |= TIOCM_RNG;
+	if (status & UART_MSR_DSR)
+		ret |= TIOCM_DSR;
+	if (status & UART_MSR_CTS)
+		ret |= TIOCM_CTS;
+	return ret;
+}
+
+static void ast25xx_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
+{
+	struct ast_uart_port *up = to_ast_dma_uart_port(port);
+	unsigned char mcr = 0;
+
+	mctrl = 0;
+
+	if (mctrl & TIOCM_RTS)
+		mcr |= UART_MCR_RTS;
+	if (mctrl & TIOCM_DTR)
+		mcr |= UART_MCR_DTR;
+	if (mctrl & TIOCM_OUT1)
+		mcr |= UART_MCR_OUT1;
+	if (mctrl & TIOCM_OUT2)
+		mcr |= UART_MCR_OUT2;
+	if (mctrl & TIOCM_LOOP)
+		mcr |= UART_MCR_LOOP;
+
+	mcr = (mcr & up->mcr_mask) | up->mcr_force | up->mcr;
+
+	ast_serial_out(up, UART_MCR, mcr);
+}
+
+static void ast25xx_uart_break_ctl(struct uart_port *port, int break_state)
+{
+	struct ast_uart_port *up = to_ast_dma_uart_port(port);
+	unsigned long flags;
+
+	spin_lock_irqsave(&up->port.lock, flags);
+	if (break_state == -1)
+		up->lcr |= UART_LCR_SBC;
+	else
+		up->lcr &= ~UART_LCR_SBC;
+	ast_serial_out(up, UART_LCR, up->lcr);
+	spin_unlock_irqrestore(&up->port.lock, flags);
+}
+
+static int ast25xx_uart_startup(struct uart_port *port)
+{
+	struct ast_uart_port *up = to_ast_dma_uart_port(port);
+	// TX DMA
+	struct circ_buf *xmit = &up->port.state->xmit;
+	unsigned long flags;
+	unsigned char lsr, iir;
+	int retval;
+	int irq_flags = up->port.flags & UPF_SHARE_IRQ ? IRQF_SHARED : 0;
+
+	trace_printk("line[%d]\n", port->line);
+	up->capabilities = uart_config[up->port.type].flags;
+	up->mcr = 0;
+	/*
+	 * Clear the FIFO buffers and disable them.
+	 * (they will be reenabled in set_termios())
+	 */
+	ast25xx_uart_clear_fifos(up);
+
+	/*
+	 * Clear the interrupt registers.
+	 */
+	(void)serial_inp(up, UART_LSR);
+	(void)serial_inp(up, UART_RX);
+	(void)serial_inp(up, UART_IIR);
+	(void)serial_inp(up, UART_MSR);
+
+	ast_uart_irq[0].up = up;
+	retval = request_irq(up->port.irq, ast_uart_interrupt, irq_flags,
+		       "ast-uart-dma", ast_uart_irq);
+	if (retval)
+		return retval;
+
+	/*
+	 * Now, initialize the UART
+	 */
+	serial_outp(up, UART_LCR, UART_LCR_WLEN8);
+
+	spin_lock_irqsave(&up->port.lock, flags);
+	up->port.mctrl |= TIOCM_OUT2;
+
+	ast25xx_uart_set_mctrl(&up->port, up->port.mctrl);
+
+	/*
+	 * Do a quick test to see if we receive an
+	 * interrupt when we enable the TX irq.
+	 */
+	serial_outp(up, UART_IER, UART_IER_THRI);
+	lsr = ast_serial_in(up, UART_LSR);
+	iir = ast_serial_in(up, UART_IIR);
+	serial_outp(up, UART_IER, 0);
+
+	if (lsr & UART_LSR_TEMT && iir & UART_IIR_NO_INT) {
+		if (!(up->bugs & UART_BUG_TXEN)) {
+			up->bugs |= UART_BUG_TXEN;
+			pr_debug("ttyDMA%d-enabling bad tx status\n",
+								 port->line);
+		}
+	} else {
+		up->bugs &= ~UART_BUG_TXEN;
+	}
+
+	spin_unlock_irqrestore(&up->port.lock, flags);
+
+	/*
+	 * Clear the interrupt registers again for luck, and clear the
+	 * saved flags to avoid getting false values from polling
+	 * routines or the previous session.
+	 */
+	serial_inp(up, UART_LSR);
+	serial_inp(up, UART_RX);
+	serial_inp(up, UART_IIR);
+	serial_inp(up, UART_MSR);
+	up->lsr_saved_flags = 0;
+	up->msr_saved_flags = 0;
+
+	// RX DMA
+	up->rx_dma_buf.head = 0;
+	up->rx_dma_buf.tail = 0;
+	up->port.icount.rx = 0;
+
+	up->tx_done = 1;
+	up->tx_count = 0;
+
+	up->rx_dma_buf.head = 0;
+	up->rx_dma_buf.tail = 0;
+#ifndef CONFIG_AST_UART_DMA_RX_INTERRUPT
+	up->workaround = 0;
+#endif
+	ast_uart_rx_sdma_ctrl(up->dma_channel, AST_UART_DMAOP_STOP);
+	ast_uart_rx_sdma_ctrl(up->dma_channel, AST_UART_DMAOP_TRIGGER);
+#ifndef CONFIG_AST_UART_DMA_RX_INTERRUPT
+	add_timer(&up->rx_timer);
+#endif
+	up->tx_dma_buf.head = 0;
+	up->tx_dma_buf.tail = 0;
+	up->tx_dma_buf.buf = xmit->buf;
+
+	trace_printk("head:0x%x tail:0x%x\n", xmit->head, xmit->tail);
+	xmit->head = 0;
+	xmit->tail = 0;
+
+	up->dma_tx_addr = dma_map_single(port->dev, up->tx_dma_buf.buf,
+				   UART_XMIT_SIZE, DMA_TO_DEVICE);
+
+	ast_uart_tx_sdma_ctrl(up->dma_channel, AST_UART_DMAOP_STOP);
+	ast_uart_tx_sdma_enqueue(up->dma_channel, up->dma_tx_addr);
+	ast_uart_tx_sdma_update(up->dma_channel, 0);
+	ast_uart_tx_sdma_ctrl(up->dma_channel, AST_UART_DMAOP_TRIGGER);
+
+	return 0;
+}
+
+static void ast25xx_uart_shutdown(struct uart_port *port)
+{
+	struct ast_uart_port *up = to_ast_dma_uart_port(port);
+	unsigned long flags;
+
+	trace_printk("line[%d]\n", port->line);
+
+	up->ier = 0;
+	serial_outp(up, UART_IER, 0);
+
+	spin_lock_irqsave(&up->port.lock, flags);
+	up->port.mctrl &= ~TIOCM_OUT2;
+
+	ast25xx_uart_set_mctrl(&up->port, up->port.mctrl);
+	spin_unlock_irqrestore(&up->port.lock, flags);
+
+	/*
+	 * Disable break condition and FIFOs
+	 */
+	ast_serial_out(up, UART_LCR, serial_inp(up, UART_LCR) & ~UART_LCR_SBC);
+	ast25xx_uart_clear_fifos(up);
+
+	(void)ast_serial_in(up, UART_RX);
+
+	ast_uart_rx_sdma_ctrl(up->dma_channel, AST_UART_DMAOP_PAUSE);
+#ifndef CONFIG_AST_UART_DMA_RX_INTERRUPT
+	del_timer_sync(&up->rx_timer);
+#endif
+	free_irq(up->port.irq, ast_uart_irq);
+}
+
+static unsigned int ast25xx_uart_get_divisor(struct uart_port *port,
+					   unsigned int baud)
+{
+	unsigned int quot;
+
+	quot = uart_get_divisor(port, baud);
+	return quot;
+}
+
+static void ast25xx_uart_set_termios(struct uart_port *port,
+				   struct ktermios *termios,
+				   struct ktermios *old)
+{
+	struct ast_uart_port *up = to_ast_dma_uart_port(port);
+	unsigned char cval, fcr = 0;
+	unsigned long flags;
+	unsigned int baud, quot;
+
+	switch (termios->c_cflag & CSIZE) {
+	case CS5:
+		cval = UART_LCR_WLEN5;
+		break;
+	case CS6:
+		cval = UART_LCR_WLEN6;
+		break;
+	case CS7:
+		cval = UART_LCR_WLEN7;
+		break;
+	default:
+	case CS8:
+		cval = UART_LCR_WLEN8;
+		break;
+	}
+
+	if (termios->c_cflag & CSTOPB)
+		cval |= UART_LCR_STOP;
+	if (termios->c_cflag & PARENB)
+		cval |= UART_LCR_PARITY;
+	if (!(termios->c_cflag & PARODD))
+		cval |= UART_LCR_EPAR;
+#ifdef CMSPAR
+	if (termios->c_cflag & CMSPAR)
+		cval |= UART_LCR_SPAR;
+#endif
+
+	/*
+	 * Ask the core to calculate the divisor for us.
+	 */
+	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk / 16);
+	quot = ast25xx_uart_get_divisor(port, baud);
+
+	if (up->capabilities & UART_CAP_FIFO && up->port.fifosize > 1) {
+		if (baud < 2400)
+			fcr = UART_FCR_ENABLE_FIFO | UART_FCR_TRIGGER_1;
+		else
+			fcr = uart_config[up->port.type].fcr;
+	}
+
+	/*
+	 * Ok, we're now changing the port state.  Do it with
+	 * interrupts disabled.
+	 */
+	spin_lock_irqsave(&up->port.lock, flags);
+
+	/*
+	 * Update the per-port timeout.
+	 */
+	uart_update_timeout(port, termios->c_cflag, baud);
+
+	up->port.read_status_mask = UART_LSR_OE | UART_LSR_THRE | UART_LSR_DR;
+	if (termios->c_iflag & INPCK)
+		up->port.read_status_mask |= UART_LSR_FE | UART_LSR_PE;
+	if (termios->c_iflag & (BRKINT | PARMRK))
+		up->port.read_status_mask |= UART_LSR_BI;
+
+	/*
+	 * Characters to ignore
+	 */
+	up->port.ignore_status_mask = 0;
+	if (termios->c_iflag & IGNPAR)
+		up->port.ignore_status_mask |= UART_LSR_PE | UART_LSR_FE;
+	if (termios->c_iflag & IGNBRK) {
+		up->port.ignore_status_mask |= UART_LSR_BI;
+	/*
+	 * If we're ignoring parity and break indicators,
+	 * ignore overruns too (for real raw support).
+	 */
+	if (termios->c_iflag & IGNPAR)
+		up->port.ignore_status_mask |= UART_LSR_OE;
+	}
+
+	/*
+	 * ignore all characters if CREAD is not set
+	 */
+	if ((termios->c_cflag & CREAD) == 0)
+		up->port.ignore_status_mask |= UART_LSR_DR;
+
+	/*
+	 * CTS flow control flag and modem status interrupts
+	 */
+	up->ier &= ~UART_IER_MSI;
+	if (UART_ENABLE_MS(&up->port, termios->c_cflag))
+		up->ier |= UART_IER_MSI;
+
+	ast_serial_out(up, UART_IER, up->ier);
+
+	serial_outp(up, UART_LCR, cval | UART_LCR_DLAB); /* set DLAB */
+
+	serial_dl_write(up, quot);
+
+	/*
+	 * LCR DLAB must be set to enable 64-byte FIFO mode. If the FCR
+	 * is written without DLAB set, this mode will be disabled.
+	 */
+
+	serial_outp(up, UART_LCR, cval); /* reset DLAB */
+	up->lcr = cval;                  /* Save LCR */
+	if (fcr & UART_FCR_ENABLE_FIFO) {
+	/* emulated UARTs (Lucent Venus 167x) need two steps */
+		serial_outp(up, UART_FCR, UART_FCR_ENABLE_FIFO);
+	}
+	serial_outp(up, UART_FCR, fcr); /* set fcr */
+	ast25xx_uart_set_mctrl(&up->port, up->port.mctrl);
+	spin_unlock_irqrestore(&up->port.lock, flags);
+	/* Don't rewrite B0 */
+	if (tty_termios_baud_rate(termios))
+		tty_termios_encode_baud_rate(termios, baud, baud);
+}
+
+static void ast25xx_uart_pm(struct uart_port *port, unsigned int state,
+			  unsigned int oldstate)
+{
+	struct ast_uart_port *p = (struct ast_uart_port *)port;
+
+	if (p->pm)
+		p->pm(port, state, oldstate);
+}
+
+/*
+ * Resource handling.
+ */
+static int ast25xx_uart_request_std_resource(struct ast_uart_port *up)
+{
+	unsigned int size = 8 << up->port.regshift;
+	int ret = 0;
+
+	if (!up->port.mapbase)
+		return ret;
+
+	if (!request_mem_region(up->port.mapbase, size, "ast-uart-dma")) {
+		ret = -EBUSY;
+		return ret;
+	}
+
+	if (up->port.flags & UPF_IOREMAP) {
+		up->port.membase = ioremap_nocache(up->port.mapbase, size);
+		if (!up->port.membase) {
+			release_mem_region(up->port.mapbase, size);
+			ret = -ENOMEM;
+			return ret;
+		}
+	}
+	return ret;
+}
+
+static void ast25xx_uart_release_std_resource(struct ast_uart_port *up)
+{
+	unsigned int size = 8 << up->port.regshift;
+
+	if (!up->port.mapbase)
+		return;
+
+	if (up->port.flags & UPF_IOREMAP) {
+		iounmap(up->port.membase);
+		up->port.membase = NULL;
+	}
+	release_mem_region(up->port.mapbase, size);
+}
+
+static void ast25xx_uart_release_port(struct uart_port *port)
+{
+	struct ast_uart_port *up = (struct ast_uart_port *)port;
+
+	ast25xx_uart_release_std_resource(up);
+}
+
+static int ast25xx_uart_request_port(struct uart_port *port)
+{
+	struct ast_uart_port *up = (struct ast_uart_port *)port;
+	int ret;
+
+	ret = ast25xx_uart_request_std_resource(up);
+	if (ret == 0)
+		ast25xx_uart_release_std_resource(up);
+
+	return ret;
+}
+
+static void ast25xx_uart_config_port(struct uart_port *port, int flags)
+{
+	struct ast_uart_port *up = (struct ast_uart_port *)port;
+	int ret;
+
+	/*
+	 * Find the region that we can probe for.  This in turn
+	 * tells us whether we can probe for the type of port.
+	 */
+	ret = ast25xx_uart_request_std_resource(up);
+	if (ret < 0)
+		return;
+
+	if (flags & UART_CONFIG_TYPE)
+		autoconfig(up);
+
+	if (up->port.type == PORT_UNKNOWN)
+		ast25xx_uart_release_std_resource(up);
+}
+
+static int ast25xx_uart_verify_port(struct uart_port *port,
+				  struct serial_struct *ser)
+{
+	return 0;
+}
+
+static const char *ast25xx_uart_type(struct uart_port *port)
+{
+	int type = port->type;
+
+	if (type >= ARRAY_SIZE(uart_config))
+		type = 0;
+	return uart_config[type].name;
+}
+
+static const struct uart_ops ast25xx_uart_pops = {
+	.tx_empty = ast25xx_uart_tx_empty,
+	.set_mctrl = ast25xx_uart_set_mctrl,
+	.get_mctrl = ast25xx_uart_get_mctrl,
+	.stop_tx = ast25xx_uart_stop_tx,
+	.start_tx = ast25xx_uart_start_tx,
+	.stop_rx = ast25xx_uart_stop_rx,
+	.enable_ms = ast25xx_uart_enable_ms,
+	.break_ctl = ast25xx_uart_break_ctl,
+	.startup = ast25xx_uart_startup,
+	.shutdown = ast25xx_uart_shutdown,
+	.set_termios = ast25xx_uart_set_termios,
+	.pm = ast25xx_uart_pm,
+	.type = ast25xx_uart_type,
+	.release_port = ast25xx_uart_release_port,
+	.request_port = ast25xx_uart_request_port,
+	.config_port = ast25xx_uart_config_port,
+	.verify_port = ast25xx_uart_verify_port,
+};
+
+static void __init ast25xx_uart_isa_init_ports(void)
+{
+	static int first = 1;
+	int i;
+
+	if (!first)
+		return;
+	first = 0;
+
+	for (i = 0; i < nr_uarts; i++) {
+		struct ast_uart_port *up = &ast_uart_ports[i];
+
+		up->port.line = i;
+		spin_lock_init(&up->port.lock);
+
+	/*
+	 * ALPHA_KLUDGE_MCR needs to be killed.
+	 */
+		up->mcr_mask = ~ALPHA_KLUDGE_MCR;
+		up->mcr_force = ALPHA_KLUDGE_MCR;
+		up->port.ops = &ast25xx_uart_pops;
+	}
+}
+
+static void __init ast25xx_uart_register_ports(struct uart_driver *drv,
+					     struct device *dev)
+{
+	int i;
+
+	ast25xx_uart_isa_init_ports();
+
+	for (i = 0; i < nr_uarts; i++) {
+		struct ast_uart_port *up = &ast_uart_ports[i];
+
+		up->port.dev = dev;
+		uart_add_one_port(drv, &up->port);
+	}
+}
+
+
+static struct ast_uart_port *
+ast25xx_uart_find_match_or_unused(struct uart_port *port)
+{
+	int i;
+
+	/*
+	 * First, find a port entry which matches.
+	 */
+	for (i = 0; i < nr_uarts; i++)
+		if (uart_match_port(&ast_uart_ports[i].port, port))
+			return &ast_uart_ports[i];
+
+	/*
+	 * We didn't find a matching entry, so look for the first
+	 * free entry.  We look for one which hasn't been previously
+	 * used (indicated by zero iobase).
+	 */
+	for (i = 0; i < nr_uarts; i++)
+		if (ast_uart_ports[i].port.type == PORT_UNKNOWN &&
+				ast_uart_ports[i].port.iobase == 0)
+			return &ast_uart_ports[i];
+
+	/*
+	 * That also failed.  Last resort is to find any entry which
+	 * doesn't have a real port associated with it.
+	 */
+	for (i = 0; i < nr_uarts; i++)
+		if (ast_uart_ports[i].port.type == PORT_UNKNOWN)
+			return &ast_uart_ports[i];
+
+	return NULL;
+}
+
+/*
+ * This "device" covers _all_ ISA 8250-compatible serial devices listed
+ * in the table in include/asm/serial.h
+ */
+static struct platform_device *ast25xx_uart_platform_obj_dev;
+
+static struct uart_driver ast25xx_uart_reg = {
+	.owner = THIS_MODULE,
+	.driver_name = "ast-uart-dma",
+	.dev_name = "ttyDMA",
+	.major = TTY_AST_MAJOR,
+	.minor = TTY_AST_MINOR,
+	.nr = UART_DMA_NR,
+	.cons = SERIAL8250_CONSOLE,
+};
+
+
+/*
+ *Configure the serial port specified by the request. If the
+ *port exists and is in use, it is hung up and unregistered
+ *first.
+ *
+ *The port is then probed and if necessary the IRQ is autodetected
+ *If this fails an error is returned.
+ *
+ *On success the port is ready to use and the line number is returned.
+ */
+int ast_uart_register_port(struct uart_port *port)
+{
+	struct ast_uart_port *up;
+	int ret = -ENOSPC;
+
+	if (port->uartclk == 0)
+		return -EINVAL;
+
+	mutex_lock(&ast_uart_mutex);
+
+	up = ast25xx_uart_find_match_or_unused(port);
+	if (up) {
+		uart_remove_one_port(&ast25xx_uart_reg, &up->port);
+		up->port.iobase = port->iobase;
+		up->port.membase = port->membase;
+		up->port.irq = port->irq;
+		up->port.uartclk = port->uartclk;
+		up->port.fifosize = port->fifosize;
+		up->port.regshift = port->regshift;
+		up->port.iotype = port->iotype;
+		up->port.flags = port->flags | UPF_BOOT_AUTOCONF;
+		up->port.mapbase = port->mapbase;
+		up->port.private_data = port->private_data;
+		if (port->dev)
+			up->port.dev = port->dev;
+
+		ret = uart_add_one_port(&ast25xx_uart_reg, &up->port);
+		if (ret == 0)
+			ret = up->port.line;
+
+		spin_lock_init(&up->lock);
+
+		tasklet_init(&up->tx_tasklet, ast_uart_tx_sdma_tasklet_func,
+		 (unsigned long)up);
+#ifdef CONFIG_AST_UART_DMA_RX_INTERRUPT
+		tasklet_init(&up->rx_tasklet, ast_uart_rx_sdma_tasklet_func,
+		 (unsigned long)up);
+#else
+		up->rx_timer.expires = jiffies + (HZ);
+		up->rx_timer.function = ast_uart_rx_timer_func;
+		timer_setup(&up->rx_timer, ast_uart_rx_timer_func, 0);
+#endif
+	}
+
+	mutex_unlock(&ast_uart_mutex);
+	return ret;
+}
+
+void ast_uart_unregister_port(int line)
+{
+	struct ast_uart_port *up = &ast_uart_ports[line];
+
+	mutex_lock(&ast_uart_mutex);
+	uart_remove_one_port(&ast25xx_uart_reg, &up->port);
+	if (ast25xx_uart_platform_obj_dev) {
+		up->port.flags &= ~UPF_BOOT_AUTOCONF;
+		up->port.type = PORT_UNKNOWN;
+		up->port.dev = &ast25xx_uart_platform_obj_dev->dev;
+		uart_add_one_port(&ast25xx_uart_reg, &up->port);
+	} else {
+		up->port.dev = NULL;
+	}
+	mutex_unlock(&ast_uart_mutex);
+}
+
+/*
+ * Register a set of serial devices attached to a platform device.  The
+ * list is terminated with a zero flags entry, which means we expect
+ * all entries to have at least UPF_BOOT_AUTOCONF set.
+ */
+static int port_index;
+struct clk *clk;
+
+static int ast25xx_uart_probe(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	struct uart_port port;
+	struct ast_uart_port *up = NULL;
+
+	int ret = 0;
+	u32 read, dma_channel = 0;
+	struct resource *res;
+
+	if (UART_XMIT_SIZE > DMA_BUFF_SIZE)
+		trace_printk("UART_XMIT_SIZE > DMA_BUFF_SIZE : Please Check\n");
+
+	up = &ast_uart_ports[port_index];
+	memset(&port, 0, sizeof(struct uart_port));
+
+	res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
+	if (res == NULL) {
+		dev_err(&pdev->dev, "IRQ resource not found");
+		return -ENODEV;
+	}
+	port.irq = res->start;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res) {
+		dev_err(&pdev->dev, "Register base not found");
+		return -ENODEV;
+	}
+	port.mapbase = res->start;
+
+	clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(clk)) {
+		dev_err(&pdev->dev, "missing controller clock");
+		return PTR_ERR(clk);
+	}
+	ret = clk_prepare_enable(clk);
+	if (ret) {
+		dev_err(&pdev->dev, "failed enabling DMA UART Clk: %d\n", ret);
+		return ret;
+	}
+	port.uartclk = clk_get_rate(clk);
+
+	ret = of_property_read_u32(np, "reg-shift", &read);
+	if (ret) {
+		dev_err(&pdev->dev, "Failed to read reg-shift from DT");
+		return -ret;
+	}
+	port.regshift = read;
+	ret = of_property_read_u32(np, "dma-channel", &read);
+	if (ret) {
+		dev_err(&pdev->dev, "Failed to read dma-channel from DT");
+		return -ret;
+	}
+	dma_channel = read;
+	up->dma_channel = dma_channel;
+	port.iotype = UPIO_MEM;
+	port.flags = UPF_IOREMAP | UPF_BOOT_AUTOCONF | UPF_SKIP_TEST;
+	port.dev        = &pdev->dev;
+	//port.private_data = up->dma_channel;
+	if (share_irqs)
+		port.flags |= UPF_SHARE_IRQ;
+
+	ret = ast_uart_register_port(&port);
+	if (ret < 0) {
+		dev_err(&pdev->dev,
+		"unable to registr port at index%d (IO%lx MEM%llx IRQ%d):%d\n",
+		 port_index,	port.iobase, (unsigned long long)port.mapbase,
+								port.irq, ret);
+		return ret;
+	}
+
+#ifdef CONFIG_AST_UART_DMA_RX_INTERRUPT
+	up->rx_dma_buf.buf =
+	ast_uart_rx_sdma_request(up->dma_channel, ast_uart_rx_buffdone,
+			       up);
+	if (up->rx_dma_buf.buf < 0) {
+		trace_printk("Error : failed to get rx dma channel[%d]\n",
+						 up->dma_channel);
+		goto out_ast_uart_unregister_port;
+	}
+
+#else
+	up->rx_dma_buf.buf = ast_uart_rx_sdma_request(
+				up->dma_channel, up);
+	if (up->rx_dma_buf.buf < 0) {
+		trace_printk("Error : failed to get rx dma channel[%d]\n",
+						 up->dma_channel);
+		goto out_ast_uart_unregister_port;
+	}
+#endif
+	ret = ast_uart_tx_sdma_request(up->dma_channel,
+		ast_uart_tx_buffdone, up);
+	if (ret < 0) {
+		pr_debug("Error : failed to get tx dma channel[%d]\n",
+						 up->dma_channel);
+		goto out_ast_uart_unregister_port;
+	}
+
+	up->ast_uart_pdev = pdev;
+	port_index++;
+	return 0;
+
+out_ast_uart_unregister_port:
+	up = &ast_uart_ports[port_index];
+
+	if (up->port.dev == &pdev->dev)
+		ast_uart_unregister_port(up->port.line);
+	return ret;
+}
+
+/*
+ * Remove serial ports registered against a platform device.
+ */
+static int ast25xx_uart_remove(struct platform_device *pdev)
+{
+	int i;
+
+	for (i = 0; i < nr_uarts; i++) {
+		struct ast_uart_port *up = &ast_uart_ports[i];
+
+		if (up->port.dev == &pdev->dev)
+			ast_uart_unregister_port(i);
+	}
+	return 0;
+}
+
+static int ast25xx_uart_suspend(struct platform_device *pdev,
+			      pm_message_t state)
+{
+	int i;
+
+	for (i = 0; i < UART_DMA_NR; i++) {
+		struct ast_uart_port *up = &ast_uart_ports[i];
+
+		if (up->port.type != PORT_UNKNOWN && up->port.dev == &pdev->dev)
+			uart_suspend_port(&ast25xx_uart_reg, &up->port);
+	}
+
+	return 0;
+}
+
+static int ast25xx_uart_resume(struct platform_device *pdev)
+{
+	int i;
+
+	for (i = 0; i < UART_DMA_NR; i++) {
+		struct ast_uart_port *up = &ast_uart_ports[i];
+
+	if (up->port.type != PORT_UNKNOWN && up->port.dev == &pdev->dev)
+		serial8250_resume_port(i);
+	}
+
+	return 0;
+}
+static const struct of_device_id ast_serial_dt_ids[] = {
+	{ .compatible = "aspeed,ast-sdma-uart", },
+	{ /* sentinel */ }
+};
+
+static struct platform_driver ast25xx_uart_ast_dma_driver = {
+	.probe = ast25xx_uart_probe,
+	.remove = ast25xx_uart_remove,
+	.suspend = ast25xx_uart_suspend,
+	.resume = ast25xx_uart_resume,
+	.driver = {
+	    .name = "ast2500-uart-dma-drv",
+	    .of_match_table = of_match_ptr(ast_serial_dt_ids),
+	},
+};
+
+static int __init ast_uart_init(void)
+{
+	int ret;
+
+	if (nr_uarts > UART_DMA_NR)
+		nr_uarts = UART_DMA_NR;
+	ret = ast_uart_sdma_probe();
+	if (ret) {
+		pr_err("ast_uart_sdma_probe Failed ret = %d\n", ret);
+		goto out;
+	}
+	pr_debug("UART driver with DMA%d ports IRQ sharing %sabled\n",
+		nr_uarts, share_irqs ? "en" : "dis");
+
+	spin_lock_init(&ast_uart_irq[0].lock);
+
+	ret = uart_register_driver(&ast25xx_uart_reg);
+	if (ret)
+		goto out;
+
+	ast25xx_uart_platform_obj_dev =
+	platform_device_alloc("ast-uart-dma", PLAT8250_DEV_LEGACY);
+	if (!ast25xx_uart_platform_obj_dev) {
+		ret = -ENOMEM;
+		goto unreg_uart_drv;
+	}
+
+	ret = platform_device_add(ast25xx_uart_platform_obj_dev);
+	if (ret)
+		goto put_dev;
+
+	ast25xx_uart_register_ports(&ast25xx_uart_reg,
+				&ast25xx_uart_platform_obj_dev->dev);
+
+	ret = platform_driver_register(&ast25xx_uart_ast_dma_driver);
+	if (ret == 0)
+		goto out;
+
+	platform_device_del(ast25xx_uart_platform_obj_dev);
+put_dev:
+	platform_device_put(ast25xx_uart_platform_obj_dev);
+unreg_uart_drv:
+	uart_unregister_driver(&ast25xx_uart_reg);
+out:
+	return ret;
+}
+
+static void __exit ast_uart_exit(void)
+{
+	struct platform_device *isa_dev = ast25xx_uart_platform_obj_dev;
+
+	ast25xx_uart_platform_obj_dev = NULL;
+	platform_driver_unregister(&ast25xx_uart_ast_dma_driver);
+	platform_device_unregister(isa_dev);
+	uart_unregister_driver(&ast25xx_uart_reg);
+}
+
+module_init(ast_uart_init);
+module_exit(ast_uart_exit);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Aspeed's AST2500 DMA UART driver");
-- 
2.17.1

Re: [patch v4 1/5] AST2500 DMA UART driver

[Greg KH]

On Fri, Jul 26, 2019 at 06:57:16PM +0530, sudheer.v wrote:
> From: sudheer veliseti <sudheer.open@gmail.com>
> 
> UART driver for Aspeed's bmc chip AST2500
> 
> Design approch:
> AST2500 has dedicated Uart DMA controller which has 12 sets of Tx and RX channels
> connected to UART controller directly.
> Since the DMA controller have dedicated buffers and registers,
> there would be little benifit in adding DMA framework overhead.
> So the software for DMA controller is included within the UART driver itself.
> 
> implementation details:
> 'struct ast_uart_port' is populated and registered with uart_core.
> code is organised into two layers UART-layer and DMA-Layer,both of them are
> in the same file.UART-layer requests Rx and Tx dma channels
> and registers callbacks with DMA controller software Layer
> Interrupt service routine for DMA controller is the crucial one for Handling all
> the tx and rx data. ISRs installed for individual uarts are just dummy,and are helpful 
> only to report any spurious interrupts in hardware.
> 
> 
> Signed-off-by: sudheer veliseti <sudheer.open@gmail.com>
> ---
> 
> Changes from v3->v4:
> - per port uart structures are registerd directly with uart core 
>   Instead of registering through 8250 Frame work,
>   ast_uart_port is registered using uart_add_one_port
> -SDMA_RX_FIX macro replaced with CONFIG_AST_UART_DMA_RX_INTERRUPT
> -ast_uart_sdma_isr : DMA interrupt handler code is improvised
> -replaced pr_debug with ftrace wherever appropriate
> -dev_err is used in all error return cases
> -uart driver structure ast25xx_uart_reg is modified
> -driver name changed to ast2500-uart-dma-drv
> -rx_timer initialisation and callback fn modified
> 
> Changes from v2->v3:
> -custom debug replaced by in kerenl dynamic debug: pr_debug 
> -change-logs added 
> 
> 
> .../tty/serial/8250/8250_ast2500_uart_dma.c   | 1901 +++++++++++++++++
>  1 file changed, 1901 insertions(+)
>  create mode 100644 drivers/tty/serial/8250/8250_ast2500_uart_dma.c
> 
> diff --git a/drivers/tty/serial/8250/8250_ast2500_uart_dma.c b/drivers/tty/serial/8250/8250_ast2500_uart_dma.c
> new file mode 100644
> index 000000000000..bc830d605372
> --- /dev/null
> +++ b/drivers/tty/serial/8250/8250_ast2500_uart_dma.c
> @@ -0,0 +1,1901 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + *  DMA UART Driver for ASPEED BMC chip: AST2500
> + *
> + *  Copyright (C) 2019 sudheer Kumar veliseti, Aspeed technology Inc.
> + *  <open.sudheer@gmail.com>

What was the copyright on the file you copied?  Please properly
attribute that here.


> + *
> + */
> +#include <linux/clk.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/module.h>
> +#include <linux/of_address.h>
> +#include <linux/of_irq.h>
> +#include <linux/tty.h>
> +#include <linux/tty_flip.h>
> +#include "8250.h"
> +
> +#define SERIAL8250_CONSOLE NULL
> +#define TTY_AST_MAJOR 204
> +#define TTY_AST_MINOR 68

Where did you get this minor number from?

> +
> +#define DMA_BUFF_SIZE		0x1000
> +#define SDMA_RX_BUFF_SIZE	0x10000
> +#define PASS_LIMIT 256
> +#define UART_DMA_NR CONFIG_AST_NR_DMA_UARTS
> +#define AST_UART_SDMA_CH 12
> +
> +/* enum ast_uart_chan_op
> + * operation codes passed to the DMA code by the user, and also used
> + * to inform the current channel owner of any changes to the system state
> + */
> +enum ast_uart_chan_op {
> +	AST_UART_DMAOP_TRIGGER,
> +	AST_UART_DMAOP_STOP,
> +	AST_UART_DMAOP_PAUSE,
> +};
> +
> +/* ast_uart_dma_cbfn: buffer callback routinei type */
> +typedef void (*ast_uart_dma_cbfn)(void *dev_id, u16 len);
> +
> +struct ast_sdma_info {
> +	u8 ch_no;
> +	u8 direction;
> +	u8 enable;
> +	void *priv;
> +	char *sdma_virt_addr;
> +	dma_addr_t dma_phy_addr;
> +	/* cdriver callbacks */
> +	ast_uart_dma_cbfn callback_fn; /* buffer done callback */
> +};
> +
> +struct ast_sdma_ch {
> +	struct ast_sdma_info tx_dma_info[AST_UART_SDMA_CH];
> +	struct ast_sdma_info rx_dma_info[AST_UART_SDMA_CH];
> +};
> +
> +struct ast_sdma {
> +	void __iomem *reg_base;
> +	int dma_irq;
> +	struct ast_sdma_ch *dma_ch;
> +	struct regmap *map;
> +};
> +
> +#define UART_TX_SDMA_EN		0x00
> +#define UART_RX_SDMA_EN		0x04
> +#define UART_SDMA_CONF		0x08 /* Misc, Buffer size  */
> +#define UART_SDMA_TIMER		0x0C
> +#define UART_TX_SDMA_REST	0x20
> +#define UART_RX_SDMA_REST	0x24
> +#define UART_TX_SDMA_IER	0x30
> +#define UART_TX_SDMA_ISR	0x34
> +#define UART_RX_SDMA_IER	0x38
> +#define UART_RX_SDMA_ISR	0x3C
> +#define UART_TX_R_POINT(x)	(0x40 + ((x) * 0x20))
> +#define UART_TX_W_POINT(x)	(0x44 + ((x) * 0x20))
> +#define UART_TX_SDMA_ADDR(x)	(0x48 + ((x) * 0x20))
> +#define UART_RX_R_POINT(x)	(0x50 + ((x) * 0x20))
> +#define UART_RX_W_POINT(x)	(0x54 + ((x) * 0x20))
> +#define UART_RX_SDMA_ADDR(x)	(0x58 + ((x) * 0x20))
> +#define SDMA_CH_EN(x)		BIT(x)
> +
> +#define SDMA_TX_BUFF_SIZE_MASK	(0x3)
> +#define SDMA_SET_TX_BUFF_SIZE(x)(x)
> +#define SDMA_BUFF_SIZE_1KB	(0x0)
> +#define SDMA_BUFF_SIZE_4KB	(0x1)
> +#define SDMA_BUFF_SIZE_16KB	(0x2)
> +#define SDMA_BUFF_SIZE_64KB	(0x3)
> +#define SDMA_RX_BUFF_SIZE_MASK	(0x3 << 2)
> +#define SDMA_SET_RX_BUFF_SIZE(x)((x) << 2)
> +#define SDMA_TIMEOUT_DIS	BIT(4)
> +
> +#define UART_SDMA11_INT		BIT(11)
> +#define UART_SDMA10_INT		BIT(10)
> +#define UART_SDMA9_INT		BIT(9)
> +#define UART_SDMA8_INT		BIT(8)
> +#define UART_SDMA7_INT		BIT(7)
> +#define UART_SDMA6_INT		BIT(6)
> +#define UART_SDMA5_INT		BIT(5)
> +#define UART_SDMA4_INT		BIT(4)
> +#define UART_SDMA3_INT		BIT(3)
> +#define UART_SDMA2_INT		BIT(2)
> +#define UART_SDMA1_INT		BIT(1)
> +#define UART_SDMA0_INT		BIT(0)
> +
> +/*
> + * Configuration:
> + *   share_irqs - whether we pass IRQF_SHARED to request_irq().
> + *   This option is unsafe when used on edge-triggered interrupts.
> + */
> +static unsigned int share_irqs = SERIAL8250_SHARE_IRQS;
> +
> +static unsigned int nr_uarts = CONFIG_AST_RUNTIME_DMA_UARTS;
> +
> +struct ast_uart_port {
> +	struct uart_port port;
> +	unsigned short capabilities; /* port capabilities */
> +	unsigned short bugs;         /* port bugs */
> +	unsigned int tx_loadsz;      /* transmit fifo load size */
> +	unsigned char acr;
> +	unsigned char ier;
> +	unsigned char lcr;
> +	unsigned char mcr;
> +	unsigned char mcr_mask;  /* mask of user bits */
> +	unsigned char mcr_force; /* mask of forced bits */
> +	struct circ_buf rx_dma_buf;
> +	struct circ_buf tx_dma_buf;
> +	unsigned char dma_channel;
> +	dma_addr_t dma_rx_addr; /* Mapped ADMA descr. table */
> +	dma_addr_t dma_tx_addr; /* Mapped ADMA descr. table */
> +#ifdef CONFIG_AST_UART_DMA_RX_INTERRUPT
> +	struct tasklet_struct rx_tasklet;
> +#else
> +	struct timer_list rx_timer;
> +	unsigned int workaround;
> +#endif
> +	struct tasklet_struct tx_tasklet;
> +	spinlock_t lock;
> +	int tx_done;
> +	int tx_count;
> +	struct platform_device *ast_uart_pdev;
> +/*
> + * Some bits in registers are cleared on a read, so they must
> + * be saved whenever the register is read but the bits will not
> + * be immediately processed.
> + */
> +#define LSR_SAVE_FLAGS UART_LSR_BRK_ERROR_BITS
> +	unsigned char lsr_saved_flags;
> +#define MSR_SAVE_FLAGS UART_MSR_ANY_DELTA
> +	unsigned char msr_saved_flags;
> +
> +	/*
> +	 * We provide a per-port pm hook.
> +	 */
> +	void (*pm)(struct uart_port *port, unsigned int state,
> +						 unsigned int old);
> +};
> +
> +static struct ast_uart_port ast_uart_ports[UART_DMA_NR];
> +
> +#define GET_DEV(ast_uart_port_priv_ptr)\
> +		(ast_uart_port_priv_ptr->ast_uart_pdev->dev)
> +
> +static inline struct ast_uart_port *
> +to_ast_dma_uart_port(struct uart_port *uart) {
> +	return container_of(uart, struct ast_uart_port, port);
> +}
> +
> +struct irq_info {
> +	spinlock_t lock;
> +	struct ast_uart_port *up;
> +};
> +
> +static struct irq_info ast_uart_irq[1];
> +static DEFINE_MUTEX(ast_uart_mutex);
> +
> +/*
> + * Here we define the default xmit fifo size used for each type of UART.
> + */
> +static const struct serial8250_config uart_config[] = {
> +	[PORT_UNKNOWN] = {
> +		.name		= "unknown",
> +		.fifo_size	= 1,
> +		.tx_loadsz	= 1,
> +	},
> +	[PORT_8250] = {
> +		.name		= "8250",
> +		.fifo_size	= 1,
> +		.tx_loadsz	= 1,
> +	},
> +	[PORT_16450] = {
> +		.name		= "16450",
> +		.fifo_size	= 1,
> +		.tx_loadsz	= 1,
> +	},
> +	[PORT_16550] = {
> +		.name		= "16550",
> +		.fifo_size	= 1,
> +		.tx_loadsz	= 1,
> +	},
> +	[PORT_16550A] = {
> +		.name		= "16550A",
> +		.fifo_size	= 16,
> +		.tx_loadsz	= 16,
> +		.fcr		= UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10
> +							| UART_FCR_DMA_SELECT,
> +		.flags		= UART_CAP_FIFO,
> +	},
> +};

I doubt you need all of these port types, right?  You only have one type
of device, please strip out _ALL_ of the unneeded code in here.  You did
a wholesale copy of the old driver, to get away with that you then need
to customize it to work properly with your hardware _AND_ take away all
code that is not needed for your hardware.

Lots of this file can be removed, please do so.

thanks,

greg k-h

Re: [patch v4 1/5] AST2500 DMA UART driver

[sudheer v]

[-- Attachment #1: Type: text/plain, Size: 10668 bytes --]

Hi  Greg,
 After modifying [ patch v4 1/5 ] , should i submit whole patchset as  v5 ?
 or replying  with this single patch modified will be enough?
 how is this done in linux community ?.

Regards
Sudheer

On Tue, Jul 30, 2019 at 9:18 PM Greg KH <gregkh@linuxfoundation.org> wrote:

> On Fri, Jul 26, 2019 at 06:57:16PM +0530, sudheer.v wrote:
> > From: sudheer veliseti <sudheer.open@gmail.com>
> >
> > UART driver for Aspeed's bmc chip AST2500
> >
> > Design approch:
> > AST2500 has dedicated Uart DMA controller which has 12 sets of Tx and RX
> channels
> > connected to UART controller directly.
> > Since the DMA controller have dedicated buffers and registers,
> > there would be little benifit in adding DMA framework overhead.
> > So the software for DMA controller is included within the UART driver
> itself.
> >
> > implementation details:
> > 'struct ast_uart_port' is populated and registered with uart_core.
> > code is organised into two layers UART-layer and DMA-Layer,both of them
> are
> > in the same file.UART-layer requests Rx and Tx dma channels
> > and registers callbacks with DMA controller software Layer
> > Interrupt service routine for DMA controller is the crucial one for
> Handling all
> > the tx and rx data. ISRs installed for individual uarts are just
> dummy,and are helpful
> > only to report any spurious interrupts in hardware.
> >
> >
> > Signed-off-by: sudheer veliseti <sudheer.open@gmail.com>
> > ---
> >
> > Changes from v3->v4:
> > - per port uart structures are registerd directly with uart core
> >   Instead of registering through 8250 Frame work,
> >   ast_uart_port is registered using uart_add_one_port
> > -SDMA_RX_FIX macro replaced with CONFIG_AST_UART_DMA_RX_INTERRUPT
> > -ast_uart_sdma_isr : DMA interrupt handler code is improvised
> > -replaced pr_debug with ftrace wherever appropriate
> > -dev_err is used in all error return cases
> > -uart driver structure ast25xx_uart_reg is modified
> > -driver name changed to ast2500-uart-dma-drv
> > -rx_timer initialisation and callback fn modified
> >
> > Changes from v2->v3:
> > -custom debug replaced by in kerenl dynamic debug: pr_debug
> > -change-logs added
> >
> >
> > .../tty/serial/8250/8250_ast2500_uart_dma.c   | 1901 +++++++++++++++++
> >  1 file changed, 1901 insertions(+)
> >  create mode 100644 drivers/tty/serial/8250/8250_ast2500_uart_dma.c
> >
> > diff --git a/drivers/tty/serial/8250/8250_ast2500_uart_dma.c
> b/drivers/tty/serial/8250/8250_ast2500_uart_dma.c
> > new file mode 100644
> > index 000000000000..bc830d605372
> > --- /dev/null
> > +++ b/drivers/tty/serial/8250/8250_ast2500_uart_dma.c
> > @@ -0,0 +1,1901 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + *  DMA UART Driver for ASPEED BMC chip: AST2500
> > + *
> > + *  Copyright (C) 2019 sudheer Kumar veliseti, Aspeed technology Inc.
> > + *  <open.sudheer@gmail.com>
>
> What was the copyright on the file you copied?  Please properly
> attribute that here.
>
>
> > + *
> > + */
> > +#include <linux/clk.h>
> > +#include <linux/dma-mapping.h>
> > +#include <linux/module.h>
> > +#include <linux/of_address.h>
> > +#include <linux/of_irq.h>
> > +#include <linux/tty.h>
> > +#include <linux/tty_flip.h>
> > +#include "8250.h"
> > +
> > +#define SERIAL8250_CONSOLE NULL
> > +#define TTY_AST_MAJOR 204
> > +#define TTY_AST_MINOR 68
>
> Where did you get this minor number from?
>
> > +
> > +#define DMA_BUFF_SIZE                0x1000
> > +#define SDMA_RX_BUFF_SIZE    0x10000
> > +#define PASS_LIMIT 256
> > +#define UART_DMA_NR CONFIG_AST_NR_DMA_UARTS
> > +#define AST_UART_SDMA_CH 12
> > +
> > +/* enum ast_uart_chan_op
> > + * operation codes passed to the DMA code by the user, and also used
> > + * to inform the current channel owner of any changes to the system
> state
> > + */
> > +enum ast_uart_chan_op {
> > +     AST_UART_DMAOP_TRIGGER,
> > +     AST_UART_DMAOP_STOP,
> > +     AST_UART_DMAOP_PAUSE,
> > +};
> > +
> > +/* ast_uart_dma_cbfn: buffer callback routinei type */
> > +typedef void (*ast_uart_dma_cbfn)(void *dev_id, u16 len);
> > +
> > +struct ast_sdma_info {
> > +     u8 ch_no;
> > +     u8 direction;
> > +     u8 enable;
> > +     void *priv;
> > +     char *sdma_virt_addr;
> > +     dma_addr_t dma_phy_addr;
> > +     /* cdriver callbacks */
> > +     ast_uart_dma_cbfn callback_fn; /* buffer done callback */
> > +};
> > +
> > +struct ast_sdma_ch {
> > +     struct ast_sdma_info tx_dma_info[AST_UART_SDMA_CH];
> > +     struct ast_sdma_info rx_dma_info[AST_UART_SDMA_CH];
> > +};
> > +
> > +struct ast_sdma {
> > +     void __iomem *reg_base;
> > +     int dma_irq;
> > +     struct ast_sdma_ch *dma_ch;
> > +     struct regmap *map;
> > +};
> > +
> > +#define UART_TX_SDMA_EN              0x00
> > +#define UART_RX_SDMA_EN              0x04
> > +#define UART_SDMA_CONF               0x08 /* Misc, Buffer size  */
> > +#define UART_SDMA_TIMER              0x0C
> > +#define UART_TX_SDMA_REST    0x20
> > +#define UART_RX_SDMA_REST    0x24
> > +#define UART_TX_SDMA_IER     0x30
> > +#define UART_TX_SDMA_ISR     0x34
> > +#define UART_RX_SDMA_IER     0x38
> > +#define UART_RX_SDMA_ISR     0x3C
> > +#define UART_TX_R_POINT(x)   (0x40 + ((x) * 0x20))
> > +#define UART_TX_W_POINT(x)   (0x44 + ((x) * 0x20))
> > +#define UART_TX_SDMA_ADDR(x) (0x48 + ((x) * 0x20))
> > +#define UART_RX_R_POINT(x)   (0x50 + ((x) * 0x20))
> > +#define UART_RX_W_POINT(x)   (0x54 + ((x) * 0x20))
> > +#define UART_RX_SDMA_ADDR(x) (0x58 + ((x) * 0x20))
> > +#define SDMA_CH_EN(x)                BIT(x)
> > +
> > +#define SDMA_TX_BUFF_SIZE_MASK       (0x3)
> > +#define SDMA_SET_TX_BUFF_SIZE(x)(x)
> > +#define SDMA_BUFF_SIZE_1KB   (0x0)
> > +#define SDMA_BUFF_SIZE_4KB   (0x1)
> > +#define SDMA_BUFF_SIZE_16KB  (0x2)
> > +#define SDMA_BUFF_SIZE_64KB  (0x3)
> > +#define SDMA_RX_BUFF_SIZE_MASK       (0x3 << 2)
> > +#define SDMA_SET_RX_BUFF_SIZE(x)((x) << 2)
> > +#define SDMA_TIMEOUT_DIS     BIT(4)
> > +
> > +#define UART_SDMA11_INT              BIT(11)
> > +#define UART_SDMA10_INT              BIT(10)
> > +#define UART_SDMA9_INT               BIT(9)
> > +#define UART_SDMA8_INT               BIT(8)
> > +#define UART_SDMA7_INT               BIT(7)
> > +#define UART_SDMA6_INT               BIT(6)
> > +#define UART_SDMA5_INT               BIT(5)
> > +#define UART_SDMA4_INT               BIT(4)
> > +#define UART_SDMA3_INT               BIT(3)
> > +#define UART_SDMA2_INT               BIT(2)
> > +#define UART_SDMA1_INT               BIT(1)
> > +#define UART_SDMA0_INT               BIT(0)
> > +
> > +/*
> > + * Configuration:
> > + *   share_irqs - whether we pass IRQF_SHARED to request_irq().
> > + *   This option is unsafe when used on edge-triggered interrupts.
> > + */
> > +static unsigned int share_irqs = SERIAL8250_SHARE_IRQS;
> > +
> > +static unsigned int nr_uarts = CONFIG_AST_RUNTIME_DMA_UARTS;
> > +
> > +struct ast_uart_port {
> > +     struct uart_port port;
> > +     unsigned short capabilities; /* port capabilities */
> > +     unsigned short bugs;         /* port bugs */
> > +     unsigned int tx_loadsz;      /* transmit fifo load size */
> > +     unsigned char acr;
> > +     unsigned char ier;
> > +     unsigned char lcr;
> > +     unsigned char mcr;
> > +     unsigned char mcr_mask;  /* mask of user bits */
> > +     unsigned char mcr_force; /* mask of forced bits */
> > +     struct circ_buf rx_dma_buf;
> > +     struct circ_buf tx_dma_buf;
> > +     unsigned char dma_channel;
> > +     dma_addr_t dma_rx_addr; /* Mapped ADMA descr. table */
> > +     dma_addr_t dma_tx_addr; /* Mapped ADMA descr. table */
> > +#ifdef CONFIG_AST_UART_DMA_RX_INTERRUPT
> > +     struct tasklet_struct rx_tasklet;
> > +#else
> > +     struct timer_list rx_timer;
> > +     unsigned int workaround;
> > +#endif
> > +     struct tasklet_struct tx_tasklet;
> > +     spinlock_t lock;
> > +     int tx_done;
> > +     int tx_count;
> > +     struct platform_device *ast_uart_pdev;
> > +/*
> > + * Some bits in registers are cleared on a read, so they must
> > + * be saved whenever the register is read but the bits will not
> > + * be immediately processed.
> > + */
> > +#define LSR_SAVE_FLAGS UART_LSR_BRK_ERROR_BITS
> > +     unsigned char lsr_saved_flags;
> > +#define MSR_SAVE_FLAGS UART_MSR_ANY_DELTA
> > +     unsigned char msr_saved_flags;
> > +
> > +     /*
> > +      * We provide a per-port pm hook.
> > +      */
> > +     void (*pm)(struct uart_port *port, unsigned int state,
> > +                                              unsigned int old);
> > +};
> > +
> > +static struct ast_uart_port ast_uart_ports[UART_DMA_NR];
> > +
> > +#define GET_DEV(ast_uart_port_priv_ptr)\
> > +             (ast_uart_port_priv_ptr->ast_uart_pdev->dev)
> > +
> > +static inline struct ast_uart_port *
> > +to_ast_dma_uart_port(struct uart_port *uart) {
> > +     return container_of(uart, struct ast_uart_port, port);
> > +}
> > +
> > +struct irq_info {
> > +     spinlock_t lock;
> > +     struct ast_uart_port *up;
> > +};
> > +
> > +static struct irq_info ast_uart_irq[1];
> > +static DEFINE_MUTEX(ast_uart_mutex);
> > +
> > +/*
> > + * Here we define the default xmit fifo size used for each type of UART.
> > + */
> > +static const struct serial8250_config uart_config[] = {
> > +     [PORT_UNKNOWN] = {
> > +             .name           = "unknown",
> > +             .fifo_size      = 1,
> > +             .tx_loadsz      = 1,
> > +     },
> > +     [PORT_8250] = {
> > +             .name           = "8250",
> > +             .fifo_size      = 1,
> > +             .tx_loadsz      = 1,
> > +     },
> > +     [PORT_16450] = {
> > +             .name           = "16450",
> > +             .fifo_size      = 1,
> > +             .tx_loadsz      = 1,
> > +     },
> > +     [PORT_16550] = {
> > +             .name           = "16550",
> > +             .fifo_size      = 1,
> > +             .tx_loadsz      = 1,
> > +     },
> > +     [PORT_16550A] = {
> > +             .name           = "16550A",
> > +             .fifo_size      = 16,
> > +             .tx_loadsz      = 16,
> > +             .fcr            = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10
> > +                                                     |
> UART_FCR_DMA_SELECT,
> > +             .flags          = UART_CAP_FIFO,
> > +     },
> > +};
>
> I doubt you need all of these port types, right?  You only have one type
> of device, please strip out _ALL_ of the unneeded code in here.  You did
> a wholesale copy of the old driver, to get away with that you then need
> to customize it to work properly with your hardware _AND_ take away all
> code that is not needed for your hardware.
>
> Lots of this file can be removed, please do so.
>
> thanks,
>
> greg k-h
>

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Re: [patch v4 1/5] AST2500 DMA UART driver

[Greg KH]

On Wed, Jul 31, 2019 at 05:06:08PM +0530, sudheer v wrote:
> Hi  Greg,
>  After modifying [ patch v4 1/5 ] , should i submit whole patchset as  v5 ?

Yes please.

thanks,

greg k-h

[patch v4 2/5] build configuration for AST2500 DMA UART driver

[sudheer.v]

From: sudheer veliseti <sudheer.open@gmail.com>

build config for DMA based UART driver in AST2500.
Total Available  UARTs in AST2500 are 4

Signed-off-by: sudheer veliseti <sudheer.open@gmail.com>
---

Changes from v3->v4:
- config name changed to SERIAL_AST_DMA_UART  
- new config AST_UART_DMA_RX_INTERRUPT  introduced 
  for selectin between  DMA interrupt based RX vs timer based uart RX

Changes in v2->v3:
- change logs added

drivers/tty/serial/8250/Kconfig  | 43 ++++++++++++++++++++++++++++++++
 drivers/tty/serial/8250/Makefile |  1 +
 2 files changed, 44 insertions(+)

diff --git a/drivers/tty/serial/8250/Kconfig b/drivers/tty/serial/8250/Kconfig
index 15c2c5463835..7052ab0f4894 100644
--- a/drivers/tty/serial/8250/Kconfig
+++ b/drivers/tty/serial/8250/Kconfig
@@ -189,6 +189,49 @@ config SERIAL_8250_RUNTIME_UARTS
 	  with the module parameter "nr_uarts", or boot-time parameter
 	  8250.nr_uarts
 
+config  SERIAL_AST_DMA_UART
+        tristate "AST UART driver with DMA"
+        select SERIAL_CORE
+        help
+          UART driver with DMA support for Aspeed BMC AST25XX.
+          this driver supports UARTs in AST2500. It uses
+          DMA channel of DMA engines present in these chips.
+          since this dma engine is used only by UARTs it is not
+          added as a separate DMA driver instead added as a layer
+          within UART driver.
+
+config AST_UART_DMA_RX_INTERRUPT
+	bool "DMA interrupt of UART RX"
+	depends on SERIAL_AST_DMA_UART
+	default y
+	help
+	  This config  is Enabled by default,which means Rx part
+	  of UART is handled by DMA interrupt.
+	  if the version of chip AST2500 doesn't support
+	  DMA interrupt based RX,then Disable this option.Refer
+	  driver code to see how Rx is handled by timer,if Rx
+	  interrupt  is not available.
+
+
+config AST_NR_DMA_UARTS
+        int "Maximum number of uart dma serial ports"
+        depends on SERIAL_AST_DMA_UART
+        default "4"
+        help
+          Set this to the number of serial ports you want the driver
+          to support.  This includes any ports discovered via ACPI or
+          PCI enumeration and any ports that may be added at run-time
+          via hot-plug, or any ISA multi-port serial cards.
+
+config AST_RUNTIME_DMA_UARTS
+        int "Number of uart dma serial ports to register at runtime"
+        depends on SERIAL_AST_DMA_UART
+        range 0 AST_NR_DMA_UARTS
+        default "4"
+        help
+          Set this to the maximum number of serial ports you want
+          the kernel to register at boot time.
+
 config SERIAL_8250_EXTENDED
 	bool "Extended 8250/16550 serial driver options"
 	depends on SERIAL_8250
diff --git a/drivers/tty/serial/8250/Makefile b/drivers/tty/serial/8250/Makefile
index 18751bc63a84..251f2e85efa1 100644
--- a/drivers/tty/serial/8250/Makefile
+++ b/drivers/tty/serial/8250/Makefile
@@ -36,6 +36,7 @@ obj-$(CONFIG_SERIAL_8250_LPSS)		+= 8250_lpss.o
 obj-$(CONFIG_SERIAL_8250_MID)		+= 8250_mid.o
 obj-$(CONFIG_SERIAL_8250_MOXA)		+= 8250_moxa.o
 obj-$(CONFIG_SERIAL_8250_PXA)		+= 8250_pxa.o
+obj-$(CONFIG_SERIAL_AST_DMA_UART)	+= 8250_ast2500_uart_dma.o
 obj-$(CONFIG_SERIAL_OF_PLATFORM)	+= 8250_of.o
 
 CFLAGS_8250_ingenic.o += -I$(srctree)/scripts/dtc/libfdt
-- 
2.17.1

[patch v4 3/5] DT nodes for AST2500 DMA UART driver

[sudheer.v]

From: sudheer veliseti <sudheer.open@gmail.com>

DT node for DMA controller(ast_uart_sdma) doesn't bind to any DMA controller driver.
This is because Software for DMA controller is not based on DMA framework,but is dedicated
and serves only UARTs in AST2500. ast_uart_sdma node is searched by compatible string in the 
driver software.basic use of this node is to provide register base address of DMA controller and DMA irq number(<50>).
IRQ of DMA controller is of crucial importance, which does RX and TX of UART data. 

uart nodes dma_uart1,2...etc binds to the platform driver.
irq numbers <9>,<32>,<33>,<34> in dma_uart nodes install ISRs which are of not much interest in uart data TX/RX .


Signed-off-by: sudheer veliseti <sudheer.open@gmail.com>
---

changes from v3->v4:
-
changes from v2->v3:
- change logs added

 arch/arm/boot/dts/aspeed-ast2500-evb.dts | 21 +++++++
 arch/arm/boot/dts/aspeed-g5.dtsi         | 71 ++++++++++++++++++++++--
 2 files changed, 88 insertions(+), 4 deletions(-)

diff --git a/arch/arm/boot/dts/aspeed-ast2500-evb.dts b/arch/arm/boot/dts/aspeed-ast2500-evb.dts
index 5dbb33c10c4f..4da09fbe94df 100644
--- a/arch/arm/boot/dts/aspeed-ast2500-evb.dts
+++ b/arch/arm/boot/dts/aspeed-ast2500-evb.dts
@@ -64,6 +64,27 @@
 	status = "okay";
 };
 
+&ast_uart_sdma {
+	status = "okay";
+};
+
+&dma_uart1 {
+	status = "okay";
+};
+
+&dma_uart2 {
+	status = "okay";
+};
+
+&dma_uart3 {
+	status = "okay";
+};
+
+&dma_uart4 {
+	status = "okay";
+};
+
+
 &mac0 {
 	status = "okay";
 
diff --git a/arch/arm/boot/dts/aspeed-g5.dtsi b/arch/arm/boot/dts/aspeed-g5.dtsi
index 674746513031..fb7b3ed463de 100644
--- a/arch/arm/boot/dts/aspeed-g5.dtsi
+++ b/arch/arm/boot/dts/aspeed-g5.dtsi
@@ -23,10 +23,10 @@
 		i2c11 = &i2c11;
 		i2c12 = &i2c12;
 		i2c13 = &i2c13;
-		serial0 = &uart1;
-		serial1 = &uart2;
-		serial2 = &uart3;
-		serial3 = &uart4;
+		serial0 = &dma_uart1;
+		serial1 = &dma_uart2;
+		serial2 = &dma_uart3;
+		serial3 = &dma_uart4;
 		serial4 = &uart5;
 		serial5 = &vuart;
 		peci0 = &peci0;
@@ -497,6 +497,69 @@
 				status = "disabled";
 			};
 
+			ast_uart_sdma: uart_sdma@1e79e000 {
+				compatible = "aspeed,ast-uart-sdma";
+				reg = <0x1e79e000 0x400>;
+				interrupts = <50>;
+				status = "disabled";
+			};
+
+			dma_uart1: dma_uart1@1e783000{
+				compatible = "aspeed,ast-sdma-uart";
+				reg = <0x1e783000 0x1000>;
+				reg-shift = <2>;
+				interrupts = <9>;
+				clocks = <&syscon ASPEED_CLK_GATE_UART1CLK>;
+				dma-channel = <0>;
+				no-loopback-test;
+				pinctrl-names = "default";
+				pinctrl-0 = <&pinctrl_txd1_default
+							 &pinctrl_rxd1_default>;
+				status = "disabled";
+			};
+
+			dma_uart2: dma_uart2@1e78d000{
+				compatible = "aspeed,ast-sdma-uart";
+				reg = <0x1e78d000 0x1000>;
+				reg-shift = <2>;
+				interrupts = <32>;
+				clocks = <&syscon ASPEED_CLK_GATE_UART2CLK>;
+				dma-channel = <1>;
+				no-loopback-test;
+				pinctrl-names = "default";
+				pinctrl-0 = <&pinctrl_txd2_default
+							 &pinctrl_rxd2_default>;
+				status = "disabled";
+			};
+
+			dma_uart3: dma_uart3@1e78e000{
+				compatible = "aspeed,ast-sdma-uart";
+				reg = <0x1e78e000 0x1000>;
+				reg-shift = <2>;
+				interrupts = <33>;
+				clocks = <&syscon ASPEED_CLK_GATE_UART3CLK>;
+				dma-channel = <2>;
+				no-loopback-test;
+				pinctrl-names = "default";
+				pinctrl-0 = <&pinctrl_txd3_default
+							 &pinctrl_rxd3_default>;
+				status = "disabled";
+			};
+
+			dma_uart4: dma_uart4@1e78f000{
+				compatible = "aspeed,ast-sdma-uart";
+				reg = <0x1e78f000 0x1000>;
+				reg-shift = <2>;
+				interrupts = <34>;
+				clocks = <&syscon ASPEED_CLK_GATE_UART4CLK>;
+				dma-channel = <3>;
+				no-loopback-test;
+				pinctrl-names = "default";
+				pinctrl-0 = <&pinctrl_txd4_default
+							 &pinctrl_rxd4_default>;
+				status = "disabled";
+			};
+
 			i2c: bus@1e78a000 {
 				compatible = "simple-bus";
 				#address-cells = <1>;
-- 
2.17.1

Re: [patch v4 3/5] DT nodes for AST2500 DMA UART driver

[Rob Herring]

On Fri, Jul 26, 2019 at 7:25 AM sudheer.v <open.sudheer@gmail.com> wrote:
>
> From: sudheer veliseti <sudheer.open@gmail.com>
>
> DT node for DMA controller(ast_uart_sdma) doesn't bind to any DMA controller driver.
> This is because Software for DMA controller is not based on DMA framework,but is dedicated
> and serves only UARTs in AST2500. ast_uart_sdma node is searched by compatible string in the
> driver software.basic use of this node is to provide register base address of DMA controller and DMA irq number(<50>).
> IRQ of DMA controller is of crucial importance, which does RX and TX of UART data.
>
> uart nodes dma_uart1,2...etc binds to the platform driver.
> irq numbers <9>,<32>,<33>,<34> in dma_uart nodes install ISRs which are of not much interest in uart data TX/RX .
>
>
> Signed-off-by: sudheer veliseti <sudheer.open@gmail.com>
> ---
>
> changes from v3->v4:
> -
> changes from v2->v3:
> - change logs added
>
>  arch/arm/boot/dts/aspeed-ast2500-evb.dts | 21 +++++++
>  arch/arm/boot/dts/aspeed-g5.dtsi         | 71 ++++++++++++++++++++++--
>  2 files changed, 88 insertions(+), 4 deletions(-)
>
> diff --git a/arch/arm/boot/dts/aspeed-ast2500-evb.dts b/arch/arm/boot/dts/aspeed-ast2500-evb.dts
> index 5dbb33c10c4f..4da09fbe94df 100644
> --- a/arch/arm/boot/dts/aspeed-ast2500-evb.dts
> +++ b/arch/arm/boot/dts/aspeed-ast2500-evb.dts
> @@ -64,6 +64,27 @@
>         status = "okay";
>  };
>
> +&ast_uart_sdma {
> +       status = "okay";
> +};
> +
> +&dma_uart1 {
> +       status = "okay";
> +};
> +
> +&dma_uart2 {
> +       status = "okay";
> +};
> +
> +&dma_uart3 {
> +       status = "okay";
> +};
> +
> +&dma_uart4 {
> +       status = "okay";
> +};
> +
> +
>  &mac0 {
>         status = "okay";
>
> diff --git a/arch/arm/boot/dts/aspeed-g5.dtsi b/arch/arm/boot/dts/aspeed-g5.dtsi
> index 674746513031..fb7b3ed463de 100644
> --- a/arch/arm/boot/dts/aspeed-g5.dtsi
> +++ b/arch/arm/boot/dts/aspeed-g5.dtsi
> @@ -23,10 +23,10 @@
>                 i2c11 = &i2c11;
>                 i2c12 = &i2c12;
>                 i2c13 = &i2c13;
> -               serial0 = &uart1;
> -               serial1 = &uart2;
> -               serial2 = &uart3;
> -               serial3 = &uart4;
> +               serial0 = &dma_uart1;
> +               serial1 = &dma_uart2;
> +               serial2 = &dma_uart3;
> +               serial3 = &dma_uart4;
>                 serial4 = &uart5;
>                 serial5 = &vuart;
>                 peci0 = &peci0;
> @@ -497,6 +497,69 @@
>                                 status = "disabled";
>                         };
>
> +                       ast_uart_sdma: uart_sdma@1e79e000 {
> +                               compatible = "aspeed,ast-uart-sdma";
> +                               reg = <0x1e79e000 0x400>;
> +                               interrupts = <50>;
> +                               status = "disabled";
> +                       };
> +
> +                       dma_uart1: dma_uart1@1e783000{
> +                               compatible = "aspeed,ast-sdma-uart";
> +                               reg = <0x1e783000 0x1000>;

Now you have 2 nodes at the same address. That's not valid. Please
build your dtbs with 'W=1' which will warn against this. Adding DMA
support should not be a whole new node. Nodes correspond to h/w
blocks, not drivers.

The old node has a reset, you don't need that? Seems strange too that
only 1 uart has a reset.

> +                               reg-shift = <2>;
> +                               interrupts = <9>;
> +                               clocks = <&syscon ASPEED_CLK_GATE_UART1CLK>;
> +                               dma-channel = <0>;

This is the channel in ast_uart_sdma? Just because you decided not to
do a DMA engine driver, doesn't mean you can't use the DMA binding.
Considering you need to map clients to the provider, use the DMA
binding.

> +                               no-loopback-test;
> +                               pinctrl-names = "default";
> +                               pinctrl-0 = <&pinctrl_txd1_default
> +                                                        &pinctrl_rxd1_default>;
> +                               status = "disabled";
> +                       };
> +
> +                       dma_uart2: dma_uart2@1e78d000{
> +                               compatible = "aspeed,ast-sdma-uart";
> +                               reg = <0x1e78d000 0x1000>;
> +                               reg-shift = <2>;
> +                               interrupts = <32>;
> +                               clocks = <&syscon ASPEED_CLK_GATE_UART2CLK>;
> +                               dma-channel = <1>;
> +                               no-loopback-test;
> +                               pinctrl-names = "default";
> +                               pinctrl-0 = <&pinctrl_txd2_default
> +                                                        &pinctrl_rxd2_default>;
> +                               status = "disabled";
> +                       };
> +
> +                       dma_uart3: dma_uart3@1e78e000{
> +                               compatible = "aspeed,ast-sdma-uart";
> +                               reg = <0x1e78e000 0x1000>;
> +                               reg-shift = <2>;
> +                               interrupts = <33>;
> +                               clocks = <&syscon ASPEED_CLK_GATE_UART3CLK>;
> +                               dma-channel = <2>;
> +                               no-loopback-test;
> +                               pinctrl-names = "default";
> +                               pinctrl-0 = <&pinctrl_txd3_default
> +                                                        &pinctrl_rxd3_default>;
> +                               status = "disabled";
> +                       };
> +
> +                       dma_uart4: dma_uart4@1e78f000{
> +                               compatible = "aspeed,ast-sdma-uart";
> +                               reg = <0x1e78f000 0x1000>;
> +                               reg-shift = <2>;
> +                               interrupts = <34>;
> +                               clocks = <&syscon ASPEED_CLK_GATE_UART4CLK>;
> +                               dma-channel = <3>;
> +                               no-loopback-test;
> +                               pinctrl-names = "default";
> +                               pinctrl-0 = <&pinctrl_txd4_default
> +                                                        &pinctrl_rxd4_default>;
> +                               status = "disabled";
> +                       };
> +
>                         i2c: bus@1e78a000 {
>                                 compatible = "simple-bus";
>                                 #address-cells = <1>;
> --
> 2.17.1
>

[patch v4 4/5] defconfig and MAINTAINERS updated for AST2500 DMA UART driver

[sudheer.v]

From: sudheer veliseti <sudheer.open@gmail.com>

defconfig changes to add DMA based UART in AST2500
Maintainers File updated.

Signed-off-by: sudheer veliseti <sudheer.open@gmail.com>
---

Changes in v4:
- config name changed to CONFIG_SERIAL_AST_DMA_UART as per convention
Changes in v3:
- Added changes logs 

MAINTAINERS                          | 12 ++++++++++++
 arch/arm/configs/aspeed_g5_defconfig |  1 +
 2 files changed, 13 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 997e27ab492f..d814a52ecf99 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1347,6 +1347,18 @@ F:	drivers/crypto/axis
 F:	drivers/pinctrl/pinctrl-artpec*
 F:	Documentation/devicetree/bindings/pinctrl/axis,artpec6-pinctrl.txt
 
+ARM/ASPEED DMA UART DRIVER
+M:	sudheer v <sudheer.open@gmail.com>
+R:	Joel Stanley <joel@jms.id.au>
+R:	Andrew Jeffery <andrew@aj.id.au>
+R:	Vinod Koul <vkoul@kernel.org>
+L:	dmaengine@vger.kernel.org
+L:	openbmc@lists.ozlabs.org
+L:	linux-aspeed@lists.ozlabs.org
+S:	Maintained
+F:	drivers/tty/serial/8250/8250_aspeed_uart_dma.c
+F:	Documentation/devicetree/bindings/serial/ast-sdma-uart.txt
+
 ARM/ASPEED I2C DRIVER
 M:	Brendan Higgins <brendanhiggins@google.com>
 R:	Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/arm/configs/aspeed_g5_defconfig b/arch/arm/configs/aspeed_g5_defconfig
index 1849cbc161b4..fc17cc9ddc00 100644
--- a/arch/arm/configs/aspeed_g5_defconfig
+++ b/arch/arm/configs/aspeed_g5_defconfig
@@ -144,6 +144,7 @@ CONFIG_SERIAL_8250=y
 CONFIG_SERIAL_8250_CONSOLE=y
 CONFIG_SERIAL_8250_NR_UARTS=6
 CONFIG_SERIAL_8250_RUNTIME_UARTS=6
+CONFIG_SERIAL_AST_DMA_UART=y
 CONFIG_SERIAL_8250_EXTENDED=y
 CONFIG_SERIAL_8250_ASPEED_VUART=y
 CONFIG_SERIAL_8250_SHARE_IRQ=y
-- 
2.17.1

[patch v4 5/5] Documentation: DT bindings AST2500 DMA UART driver

[sudheer.v]

From: sudheer veliseti <sudheer.open@gmail.com>

documentation for Dt bindings for DMA based UARTs in AST2500

Signed-off-by: sudheer veliseti <sudheer.open@gmail.com>
---

Changes in v4:
-
Changes in v3:
- change logs added

.../bindings/serial/ast2500-dma-uart.txt      | 43 +++++++++++++++++++
 1 file changed, 43 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/serial/ast2500-dma-uart.txt

diff --git a/Documentation/devicetree/bindings/serial/ast2500-dma-uart.txt b/Documentation/devicetree/bindings/serial/ast2500-dma-uart.txt
new file mode 100644
index 000000000000..6ebc60b51d4c
--- /dev/null
+++ b/Documentation/devicetree/bindings/serial/ast2500-dma-uart.txt
@@ -0,0 +1,43 @@
+DT Bindings DMA UART for AST25XX:
+
+node for DMA controller:
+                       ast_uart_sdma: uart_sdma@1e79e000 {
+                               compatible = "aspeed,ast-uart-sdma";
+                               reg = <0x1e79e000 0x400>;
+                               interrupts = <50>;
+                               status = "disabled";
+                       };
+this node  doesn't binds with any driver.
+DMA controller is handled as a separate SW layer,
+and is included in the same driver.
+This DMA controller node is included in DT
+just for Register and interrupt details
+
+
+
+node for DMA-UARTS :
+
+
+Required properties:
+
+- compatible: "aspeed,ast-sdma-uart"
+- reg: The base address of the UART register bank
+- interrupts: should contain interrupt specifier.
+- clocks: Clock driving the hardware;
+- pinctrl-0 : list of pinconfigurations
+- dma-channel: channel of DMA-controller which is used
+
+Example:
+
+	dma_uart1: dma_uart1@1e783000{
+        compatible = "aspeed,ast-sdma-uart";
+        reg = <0x1e783000 0x1000>;
+        reg-shift = <2>;
+        interrupts = <9>;
+        clocks = <&syscon ASPEED_CLK_GATE_UART1CLK>;
+        dma-channel = <0>;
+        no-loopback-test;
+        pinctrl-names = "default";
+        pinctrl-0 = <&pinctrl_txd1_default &pinctrl_rxd1_default>;
+        status = "disabled";
+        };
-- 
2.17.1