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hsu: some code cleanup
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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>
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Feng Tang authored and Greg Kroah-Hartman committed Aug 10, 2010
1 parent 669b7a0 commit 06c77e2
Showing 1 changed file with 19 additions and 66 deletions.
85 changes: 19 additions & 66 deletions drivers/serial/mfd.c
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Original file line number Diff line number Diff line change
Expand Up @@ -3,38 +3,24 @@
*
* 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
* as published by the Free Software Foundation; version 2
* 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>
Expand Down Expand Up @@ -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 */
Expand All @@ -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;
Expand All @@ -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;
Expand Down Expand Up @@ -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);
}
Expand All @@ -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);
Expand Down Expand Up @@ -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.
Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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);
Expand All @@ -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))
Expand Down Expand Up @@ -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);

Expand All @@ -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 |
Expand All @@ -655,20 +612,20 @@ 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);
return IRQ_NONE;
}

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)
Expand Down Expand Up @@ -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);
Expand Down Expand 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;
Expand Down Expand Up @@ -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
Expand Down Expand Up @@ -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;
Expand Down

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