[PATCH 05/76] 8250: Remove NR_IRQ usage

Alan Cox
2008-10-05T16:06:25Z

There are plans afoot to make the IRQ ranges dynamic. In that situation we
don't want drivers having their own huge arrays for per IRQ data so use a hash

Signed-off-by: Alan Cox <alan@redhat.com>
---

drivers/serial/68328serial.c | 11 +-----
drivers/serial/8250.c | 74 +++++++++++++++++++++++++++++++++---------
2 files changed, 60 insertions(+), 25 deletions(-)

diff --git a/drivers/serial/68328serial.c b/drivers/serial/68328serial.c
index 381b12a..277b78d 100644
--- a/drivers/serial/68328serial.c
+++ b/drivers/serial/68328serial.c
@@ -66,7 +66,6 @@
#endif

static struct m68k_serial m68k_soft[NR_PORTS];
-struct m68k_serial *IRQ_ports[NR_IRQS];

static unsigned int uart_irqs[NR_PORTS] = UART_IRQ_DEFNS;

@@ -375,15 +374,11 @@ clear_and_return:
*/
irqreturn_t rs_interrupt(int irq, void *dev_id)
{
- struct m68k_serial * info;
+ struct m68k_serial * info = dev_id;
m68328_uart *uart;
unsigned short rx;
unsigned short tx;

- info = IRQ_ports[irq];
- if(!info)
- return IRQ_NONE;
-
uart = &uart_addr[info->line];
rx = uart->urx.w;

@@ -1383,8 +1378,6 @@ rs68328_init(void)
info->port, info->irq);
printk(" is a builtin MC68328 UART\n");

- IRQ_ports[info->irq] = info; /* waste of space */
-
#ifdef CONFIG_M68VZ328
if (i > 0 )
PJSEL &= 0xCF; /* PSW enable second port output */
@@ -1393,7 +1386,7 @@ rs68328_init(void)
if (request_irq(uart_irqs[i],
rs_interrupt,
IRQF_DISABLED,
- "M68328_UART", NULL))
+ "M68328_UART", info))
panic("Unable to attach 68328 serial interrupt\n");
}
local_irq_restore(flags);
diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c
index 9ccc563..9f5e60d 100644
--- a/drivers/serial/8250.c
+++ b/drivers/serial/8250.c
@@ -39,7 +39,7 @@
#include <linux/nmi.h>
#include <linux/mutex.h>

-#include <asm/io.h>
+#include <linux/io.h>
#include <asm/irq.h>

#include "8250.h"
@@ -145,11 +145,15 @@ struct uart_8250_port {
};

struct irq_info {
- spinlock_t lock;
+ struct hlist_node node;
+ int irq;
+ spinlock_t lock; /* Protects list not the hash */
struct list_head *head;
};

-static struct irq_info irq_lists[NR_IRQS];
+#define NR_IRQ_HASH 32 /* Can be adjusted later */
+static struct hlist_head irq_lists[NR_IRQ_HASH];
+static DEFINE_MUTEX(hash_mutex); /* Used to walk the hash */

/*
* Here we define the default xmit fifo size used for each type of UART.
@@ -266,7 +270,7 @@ static const struct serial8250_config uart_config[] = {
},
};

-#if defined (CONFIG_SERIAL_8250_AU1X00)
+#if defined(CONFIG_SERIAL_8250_AU1X00)

/* Au1x00 UART hardware has a weird register layout */
static const u8 au_io_in_map[] = {
@@ -1535,15 +1539,43 @@ static void serial_do_unlink(struct irq_info *i, struct uart_8250_port *up)
BUG_ON(i->head != &up->list);
i->head = NULL;
}
-
spin_unlock_irq(&i->lock);
+ /* List empty so throw away the hash node */
+ if (i->head == NULL) {
+ hlist_del(&i->node);
+ kfree(i);
+ }
}

static int serial_link_irq_chain(struct uart_8250_port *up)
{
- struct irq_info *i = irq_lists + up->port.irq;
+ struct hlist_head *h;
+ struct hlist_node *n;
+ struct irq_info *i;
int ret, irq_flags = up->port.flags & UPF_SHARE_IRQ ? IRQF_SHARED : 0;

+ mutex_lock(&hash_mutex);
+
+ h = &irq_lists[up->port.irq % NR_IRQ_HASH];
+
+ hlist_for_each(n, h) {
+ i = hlist_entry(n, struct irq_info, node);
+ if (i->irq == up->port.irq)
+ break;
+ }
+
+ if (n == NULL) {
+ i = kzalloc(sizeof(struct irq_info), GFP_KERNEL);
+ if (i == NULL) {
+ mutex_unlock(&hash_mutex);
+ return -ENOMEM;
+ }
+ spin_lock_init(&i->lock);
+ i->irq = up->port.irq;
+ hlist_add_head(&i->node, h);
+ }
+ mutex_unlock(&hash_mutex);
+
spin_lock_irq(&i->lock);

if (i->head) {
@@ -1567,14 +1599,27 @@ static int serial_link_irq_chain(struct uart_8250_port *up)

static void serial_unlink_irq_chain(struct uart_8250_port *up)
{
- struct irq_info *i = irq_lists + up->port.irq;
+ struct irq_info *i;
+ struct hlist_node *n;
+ struct hlist_head *h;

- BUG_ON(i->head == NULL);
+ mutex_lock(&hash_mutex);
+
+ h = &irq_lists[up->port.irq % NR_IRQ_HASH];
+
+ hlist_for_each(n, h) {
+ i = hlist_entry(n, struct irq_info, node);
+ if (i->irq == up->port.irq)
+ break;
+ }

+ BUG_ON(n == NULL);
+ BUG_ON(i->head == NULL);
+
if (list_empty(i->head))
free_irq(up->port.irq, i);
-
serial_do_unlink(i, up);
+ mutex_unlock(&hash_mutex);
}

/* Base timer interval for polling */
@@ -2950,7 +2995,7 @@ EXPORT_SYMBOL(serial8250_unregister_port);

static int __init serial8250_init(void)
{
- int ret, i;
+ int ret;

if (nr_uarts > UART_NR)
nr_uarts = UART_NR;
@@ -2959,9 +3004,6 @@ static int __init serial8250_init(void)
"%d ports, IRQ sharing %sabled\n", nr_uarts,
share_irqs ? "en" : "dis");

- for (i = 0; i < NR_IRQS; i++)
- spin_lock_init(&irq_lists[i].lock);
-
ret = uart_register_driver(&serial8250_reg);
if (ret)
goto out;
@@ -2984,11 +3026,11 @@ static int __init serial8250_init(void)
goto out;

platform_device_del(serial8250_isa_devs);
- put_dev:
+put_dev:
platform_device_put(serial8250_isa_devs);
- unreg_uart_drv:
+unreg_uart_drv:
uart_unregister_driver(&serial8250_reg);
- out:
+out:
return ret;
}