[PATCH 3/4] hsu: some code cleanup

[Alan Cox <alan@linux.intel.com>]

From: Feng Tang <feng.tang@intel.com>

Major changes are:
* refine the comments in the driver
* remove unused member from structure "hsu_port"
* extended spin_lock protoction for dma mode in port_irq()

Signed-off-by: Feng Tang <feng.tang@intel.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
---

 drivers/serial/mfd.c |   85 +++++++++++---------------------------------------
 1 files changed, 19 insertions(+), 66 deletions(-)


diff --git a/drivers/serial/mfd.c b/drivers/serial/mfd.c
index 83ea831..28cb3ac 100644
--- a/drivers/serial/mfd.c
+++ b/drivers/serial/mfd.c
@@ -3,7 +3,7 @@
  *
  * Refer pxa.c, 8250.c and some other drivers in drivers/serial/
  *
- * (C) Copyright 2009 Intel Corporation
+ * (C) Copyright 2010 Intel Corporation
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
@@ -11,30 +11,16 @@
  * of the License.
  */
 
-
 /* Notes:
- * 1. there should be 2 types of register access method, one for
- *    UART ports, the other for the general purpose registers
- *
- * 2. It used to have a Irda port, but was defeatured recently
- *
- * 3. Based on the info from HSU MAS, 0/1 channel are assigned to
- *    port0, 2/3 chan to port 1, 4/5 chan to port 3. Even number
- *    chan will be read, odd chan for write
- *
- * 4. HUS supports both the 64B and 16B FIFO version, but this driver
- *    will only use 64B version
+ * 1. DMA channel allocation: 0/1 channel are assigned to port 0,
+ *    2/3 chan to port 1, 4/5 chan to port 3. Even number chans
+ *    are used for RX, odd chans for TX
  *
- * 5. In A0 stepping, UART will not support TX half empty flag, thus
- *    need add a #ifdef judgement
+ * 2. In A0 stepping, UART will not support TX half empty flag
  *
- * 6. One more bug for A0, the loopback mode won't support AFC
- *    auto-flow control
- *
- * 7. HSU has some special FCR control bits, we add it to serial_reg.h
- *
- * 8. The RI/DSR/DCD/DTR are not pinned out, DCD & DSR are always asserted,
- *    only when the HW is reset the DDCD and DDSR will be triggered
+ * 3. The RI/DSR/DCD/DTR are not pinned out, DCD & DSR are always
+ *    asserted, only when the HW is reset the DDCD and DDSR will
+ *    be triggered
  */
 
 #include <linux/module.h>
@@ -75,7 +61,7 @@ struct hsu_dma_buffer {
 
 struct hsu_dma_chan {
 	u32	id;
-	u32	dirt;	/* to or from device */
+	enum dma_data_direction	dirt;
 	struct uart_hsu_port	*uport;
 	void __iomem		*reg;
 	struct timer_list	rx_timer; /* only needed by RX channel */
@@ -102,8 +88,6 @@ struct uart_hsu_port {
 
 /* Top level data structure of HSU */
 struct hsu_port {
-	struct pci_device	*pdev;
-
 	void __iomem	*reg;
 	unsigned long	paddr;
 	unsigned long	iolen;
@@ -112,23 +96,9 @@ struct hsu_port {
 	struct uart_hsu_port	port[3];
 	struct hsu_dma_chan	chans[10];
 
-#ifdef CONFIG_DEBUG_FS
 	struct dentry *debugfs;
-#endif
 };
 
-static inline void hexdump(char *str, u8 *addr, int cnt)
-{
-	int i;
-
-	for (i = 0; i < cnt; i += 8) {
-		printk("0x%02x 0x%02x 0x%02x 0x%02x 0x%02x 0x%02x 0x%02x 0x%02x",
-			addr[i], addr[i+1], addr[i+2], addr[i+3],
-			addr[i+4], addr[i+5], addr[i+6], addr[i+7]);
-		printk("\n");
-	}
-}
-
 static inline unsigned int serial_in(struct uart_hsu_port *up, int offset)
 {
 	unsigned int val;
@@ -353,9 +323,6 @@ void hsu_dma_tx(struct uart_hsu_port *up)
 						 | (0x1 << 8)
 						 | (0x1 << 16)
 						 | (0x1 << 24));
-
-		WARN(chan_readl(up->txc, HSU_CH_CR) & 0x1,
-			"TX channel has already be started!!\n");
 		up->dma_tx_on = 1;
 		chan_writel(up->txc, HSU_CH_CR, 0x1);
 	}
@@ -367,7 +334,6 @@ void hsu_dma_tx(struct uart_hsu_port *up)
 /* The buffer is already cache coherent */
 void hsu_dma_start_rx_chan(struct hsu_dma_chan *rxc, struct hsu_dma_buffer *dbuf)
 {
-	/* Need start RX dma channel here */
 	dbuf->ofs = 0;
 
 	chan_writel(rxc, HSU_CH_BSR, 32);
@@ -426,35 +392,32 @@ void hsu_dma_rx(struct uart_hsu_port *up, u32 int_sts)
 		return;
 
 	/*
-	 * first need to know how many is already transferred,
+	 * First need to know how many is already transferred,
 	 * then check if its a timeout DMA irq, and return
 	 * the trail bytes out, push them up and reenable the
-	 * channel, better to use 2 descriptors at the same time
+	 * channel
 	 */
 
-	/* timeout IRQ, need wait some time, see Errata 2 */
+	/* Timeout IRQ, need wait some time, see Errata 2 */
 	if (int_sts & 0xf00)
 		udelay(2);
 
 	/* Stop the channel */
 	chan_writel(chan, HSU_CH_CR, 0x0);
 
-	/* We can use 2 ways to calc the actual transfer len */
 	count = chan_readl(chan, HSU_CH_D0SAR) - dbuf->dma_addr;
-
 	if (!count) {
-		/* restart the channel before we leave */
+		/* Restart the channel before we leave */
 		chan_writel(chan, HSU_CH_CR, 0x3);
 		return;
 	}
-
 	del_timer(&chan->rx_timer);
 
 	dma_sync_single_for_cpu(port->dev, dbuf->dma_addr,
 			dbuf->dma_size, DMA_FROM_DEVICE);
 
 	/*
-	 * head will only wrap around when we recycle
+	 * Head will only wrap around when we recycle
 	 * the DMA buffer, and when that happens, we
 	 * explicitly set tail to 0. So head will
 	 * always be greater than tail.
@@ -496,10 +459,6 @@ static void serial_hsu_stop_rx(struct uart_port *port)
 	}
 }
 
-/*
- * if there is error flag, should we just reset the FIFO or keeps
- * working on it
- */
 static inline void receive_chars(struct uart_hsu_port *up, int *status)
 {
 	struct tty_struct *tty = up->port.state->port.tty;
@@ -571,7 +530,6 @@ static void transmit_chars(struct uart_hsu_port *up)
 {
 	struct circ_buf *xmit = &up->port.state->xmit;
 	int count;
-	int i = 0; /* for debug use */
 
 	if (up->port.x_char) {
 		serial_out(up, UART_TX, up->port.x_char);
@@ -592,13 +550,11 @@ static void transmit_chars(struct uart_hsu_port *up)
 	 * into it won't clear the EMPT bit, so we may need be cautious 
 	 * by useing a shorter buffer
 	 */
-	/* count = up->port.fifosize; */
 	count = up->port.fifosize - 4;
 #endif
 	do {
 		serial_out(up, UART_TX, xmit->buf[xmit->tail]);
 		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-		i++;
 
 		up->port.icount.tx++;
 		if (uart_circ_empty(xmit))
@@ -628,7 +584,7 @@ static inline void check_modem_status(struct uart_hsu_port *up)
 	/* We may only get DDCD when HW init and reset */
 	if (status & UART_MSR_DDCD)
 		uart_handle_dcd_change(&up->port, status & UART_MSR_DCD);
-	/* will start/stop_tx accordingly */
+	/* Will start/stop_tx accordingly */
 	if (status & UART_MSR_DCTS)
 		uart_handle_cts_change(&up->port, status & UART_MSR_CTS);
 
@@ -647,6 +603,7 @@ static irqreturn_t port_irq(int irq, void *dev_id)
 	if (unlikely(!up->running))
 		return IRQ_NONE;
 
+	spin_lock_irqsave(&up->port.lock, flags);
 	if (up->use_dma) {
 		lsr = serial_in(up, UART_LSR);
 		if (unlikely(lsr & (UART_LSR_BI | UART_LSR_PE |
@@ -655,10 +612,10 @@ static irqreturn_t port_irq(int irq, void *dev_id)
 				"Got lsr irq while using DMA, lsr = 0x%2x\n",
 				lsr);
 		check_modem_status(up);
+		spin_unlock_irqrestore(&up->port.lock, flags);
 		return IRQ_HANDLED;
 	}
 
-	spin_lock_irqsave(&up->port.lock, flags);
 	iir = serial_in(up, UART_IIR);
 	if (iir & UART_IIR_NO_INT) {
 		spin_unlock_irqrestore(&up->port.lock, flags);
@@ -666,9 +623,9 @@ static irqreturn_t port_irq(int irq, void *dev_id)
 	}
 
 	lsr = serial_in(up, UART_LSR);
-
 	if (lsr & UART_LSR_DR)
 		receive_chars(up, &lsr);
+	check_modem_status(up);
 
 	/* lsr will be renewed during the receive_chars */
 	if (lsr & UART_LSR_THRE)
@@ -701,7 +658,6 @@ static inline void dma_chan_irq(struct hsu_dma_chan *chan)
 
 	/* Tx channel */
 	if (chan->dirt == DMA_TO_DEVICE) {
-		/* dma for irq should be done */
 		chan_writel(chan, HSU_CH_CR, 0x0);
 		up->dma_tx_on = 0;
 		hsu_dma_tx(up);
@@ -851,7 +807,6 @@ static int serial_hsu_startup(struct uart_port *port)
 	spin_unlock_irqrestore(&up->port.lock, flags);
 
 	/* DMA init */
-	/* When use DMA, TX/RX's FIFO and IRQ should be disabled */
 	if (up->use_dma) {
 		struct hsu_dma_buffer *dbuf;
 		struct circ_buf *xmit = &port->state->xmit;
@@ -1090,11 +1045,9 @@ static int serial_hsu_request_port(struct uart_port *port)
 
 static void serial_hsu_config_port(struct uart_port *port, int flags)
 {
-#if 0
 	struct uart_hsu_port *up =
 		container_of(port, struct uart_hsu_port, port);
 	up->port.type = PORT_MFD;
-#endif
 }
 
 static int
@@ -1426,7 +1379,7 @@ static void hsu_global_init(void)
 		uport->port.ops = &serial_hsu_pops;
 		uport->port.line = i;
 		uport->port.flags = UPF_IOREMAP;
-		/* make the maxim support rate to 2746800 bps */
+		/* set the scalable maxim support rate to 2746800 bps */
 		uport->port.uartclk = 115200 * 24 * 16;
 
 		uport->running = 0;