hsu: some code cleanup

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 19 insertions, 66 deletions

diff --git a/drivers/serial/mfd.c b/drivers/serial/mfd.c
index ed2bf6b14a4a..f5e7569c1773 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;