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Subject[PATCH] SPI: turn transfers from arrays to linked lists
Hi,

the patch inlined is changing the SPI core and its users to have transfers in the SPI message structure as linked list not as an array, for the reasons discussed recently in this list.
We decided to post is as a single patch, it's not that big to split it :)

Vitaly

Signed-off-by: Vitaly Wool <vwool@ru.mvista.com>
Signed-off-by: Dmitry Pervushin <dpervushin@gmail.com>

drivers/input/touchscreen/ads7846.c | 12 ++++++++----
drivers/mtd/devices/m25p80.c | 15 +++++++--------
drivers/mtd/devices/mtd_dataflash.c | 27 +++++++++++++--------------
drivers/spi/spi.c | 6 +++---
drivers/spi/spi_bitbang.c | 13 ++++---------
include/linux/spi/spi.h | 27 ++++++++++++++++-----------
6 files changed, 51 insertions(+), 49 deletions(-)

diff -uNr --exclude='patches*' --exclude=.pc linux-2.6.orig/drivers/input/touchscreen/ads7846.c linux-2.6/drivers/input/touchscreen/ads7846.c
--- linux-2.6.orig/drivers/input/touchscreen/ads7846.c 2005-12-23 13:46:16.000000000 +0300
+++ linux-2.6/drivers/input/touchscreen/ads7846.c 2005-12-23 13:34:01.000000000 +0300
@@ -155,10 +155,13 @@
struct ser_req *req = kzalloc(sizeof *req, SLAB_KERNEL);
int status;
int sample;
+ int i;

if (!req)
return -ENOMEM;

+ INIT_LIST_HEAD(&req->msg.transfers);
+
/* activate reference, so it has time to settle; */
req->xfer[0].tx_buf = &ref_on;
req->xfer[0].len = 1;
@@ -192,8 +195,8 @@
/* group all the transfers together, so we can't interfere with
* reading touchscreen state; disable penirq while sampling
*/
- req->msg.transfers = req->xfer;
- req->msg.n_transfer = 6;
+ for (i = 0; i < 6; i++)
+ list_add_tail(&req->xfer[i].link, &req->msg.transfers);

disable_irq(spi->irq);
status = spi_sync(spi, &req->msg);
@@ -398,6 +401,7 @@
struct ads7846 *ts;
struct ads7846_platform_data *pdata = spi->dev.platform_data;
struct spi_transfer *x;
+ int i;

if (!spi->irq) {
dev_dbg(&spi->dev, "no IRQ?\n");
@@ -500,8 +504,8 @@

CS_CHANGE(x[-1]);

- ts->msg.transfers = ts->xfer;
- ts->msg.n_transfer = x - ts->xfer;
+ for (i = 0; i < x - ts->xfer; i++)
+ list_add_tail(&ts->xfer[i].link, &ts->msg.transfers);
ts->msg.complete = ads7846_rx;
ts->msg.context = ts;

diff -uNr --exclude='patches*' --exclude=.pc linux-2.6.orig/drivers/mtd/devices/m25p80.c linux-2.6/drivers/mtd/devices/m25p80.c
--- linux-2.6.orig/drivers/mtd/devices/m25p80.c 2005-12-23 13:46:16.000000000 +0300
+++ linux-2.6/drivers/mtd/devices/m25p80.c 2005-12-23 15:38:19.000000000 +0300
@@ -231,7 +231,7 @@
{
struct m25p *flash = mtd_to_m25p(mtd);
struct spi_transfer t[2];
- struct spi_message m;
+ DECLARE_SPI_MESSAGE(m);

DEBUG(MTD_DEBUG_LEVEL2, "%s: %s %s 0x%08x, len %z\n", spi->dev.bus_id,
__FUNCTION__, "from", (u32) from, len);
@@ -268,12 +268,11 @@

t[0].tx_buf = flash->command;
t[0].len = sizeof(flash->command);
+ list_add_tail(&t[0].link, &m.transfers);

t[1].rx_buf = buf;
t[1].len = len;
-
- m.transfers = t;
- m.n_transfer = 2;
+ list_add_tail(&t[1].link, &m.transfers);

spi_sync(flash->spi, &m);

@@ -295,7 +294,7 @@
struct m25p *flash = mtd_to_m25p(mtd);
u32 page_offset, page_size;
struct spi_transfer t[2];
- struct spi_message m;
+ DECLARE_SPI_MESSAGE(m);

DEBUG(MTD_DEBUG_LEVEL2, "%s: %s %s 0x%08x, len %z\n", spi->dev.bus_id,
__FUNCTION__, "to", (u32) to, len);
@@ -326,12 +325,12 @@
flash->command[2] = to >> 8;
flash->command[3] = to;

+ list_add_tail(&t[0].link, &m.transfers);
+ list_add_tail(&t[1].link, &m.transfers);
+
t[0].tx_buf = flash->command;
t[0].len = sizeof(flash->command);

- m.transfers = t;
- m.n_transfer = 2;
-
/* what page do we start with? */
page_offset = to % FLASH_PAGESIZE;

diff -uNr --exclude='patches*' --exclude=.pc linux-2.6.orig/drivers/mtd/devices/mtd_dataflash.c linux-2.6/drivers/mtd/devices/mtd_dataflash.c
--- linux-2.6.orig/drivers/mtd/devices/mtd_dataflash.c 2005-12-23 13:46:16.000000000 +0300
+++ linux-2.6/drivers/mtd/devices/mtd_dataflash.c 2005-12-23 15:31:14.000000000 +0300
@@ -147,8 +147,8 @@
{
struct dataflash *priv = (struct dataflash *)mtd->priv;
struct spi_device *spi = priv->spi;
- struct spi_transfer x[1] = { { .tx_dma = 0, }, };
- struct spi_message msg;
+ struct spi_transfer x = { .tx_dma = 0, };
+ DECLARE_SPI_MESSAGE(msg);
unsigned blocksize = priv->page_size << 3;
u8 *command;

@@ -162,10 +162,9 @@
|| (instr->addr % priv->page_size) != 0)
return -EINVAL;

- x[0].tx_buf = command = priv->command;
- x[0].len = 4;
- msg.transfers = x;
- msg.n_transfer = 1;
+ x.tx_buf = command = priv->command;
+ x.len = 4;
+ list_add_tail(&x.link, &msg.transfers);

down(&priv->lock);
while (instr->len > 0) {
@@ -231,7 +230,7 @@
{
struct dataflash *priv = (struct dataflash *)mtd->priv;
struct spi_transfer x[2] = { { .tx_dma = 0, }, };
- struct spi_message msg;
+ DECLARE_SPI_MESSAGE(msg);
unsigned int addr;
u8 *command;
int status;
@@ -258,10 +257,10 @@

x[0].tx_buf = command;
x[0].len = 8;
+ list_add_tail(&x[0].link, &msg.transfers);
x[1].rx_buf = buf;
x[1].len = len;
- msg.transfers = x;
- msg.n_transfer = 2;
+ list_add_tail(&x[1].link, &msg.transfers);

down(&priv->lock);

@@ -302,7 +301,7 @@
struct dataflash *priv = (struct dataflash *)mtd->priv;
struct spi_device *spi = priv->spi;
struct spi_transfer x[2] = { { .tx_dma = 0, }, };
- struct spi_message msg;
+ DECLARE_SPI_MESSAGE(msg);
unsigned int pageaddr, addr, offset, writelen;
size_t remaining = len;
u_char *writebuf = (u_char *) buf;
@@ -320,9 +319,10 @@
if ((to + len) > mtd->size)
return -EINVAL;

+ list_add_tail(&x[0].link, &msg.transfers);
+
x[0].tx_buf = command = priv->command;
x[0].len = 4;
- msg.transfers = x;

pageaddr = ((unsigned)to / priv->page_size);
offset = ((unsigned)to % priv->page_size);
@@ -364,7 +364,6 @@
DEBUG(MTD_DEBUG_LEVEL3, "TRANSFER: (%x) %x %x %x\n",
command[0], command[1], command[2], command[3]);

- msg.n_transfer = 1;
status = spi_sync(spi, &msg);
if (status < 0)
DEBUG(MTD_DEBUG_LEVEL1, "%s: xfer %u -> %d \n",
@@ -385,8 +384,9 @@

x[1].tx_buf = writebuf;
x[1].len = writelen;
- msg.n_transfer = 2;
+ list_add_tail(&x[1].link, &msg.transfers);
status = spi_sync(spi, &msg);
+ list_del(&x[1].link);
if (status < 0)
DEBUG(MTD_DEBUG_LEVEL1, "%s: pgm %u/%u -> %d \n",
spi->dev.bus_id, addr, writelen, status);
@@ -405,7 +405,6 @@
DEBUG(MTD_DEBUG_LEVEL3, "COMPARE: (%x) %x %x %x\n",
command[0], command[1], command[2], command[3]);

- msg.n_transfer = 1;
status = spi_sync(spi, &msg);
if (status < 0)
DEBUG(MTD_DEBUG_LEVEL1, "%s: compare %u -> %d \n",
diff -uNr --exclude='patches*' --exclude=.pc linux-2.6.orig/drivers/spi/spi_bitbang.c linux-2.6/drivers/spi/spi_bitbang.c
--- linux-2.6.orig/drivers/spi/spi_bitbang.c 2005-12-23 13:46:16.000000000 +0300
+++ linux-2.6/drivers/spi/spi_bitbang.c 2005-12-23 16:13:35.000000000 +0300
@@ -242,7 +242,7 @@
struct spi_message *m;
struct spi_device *spi;
unsigned nsecs;
- struct spi_transfer *t;
+ struct spi_transfer *t = NULL;
unsigned tmp;
unsigned chipselect;
int status;
@@ -259,12 +259,11 @@
nsecs = 100;

spi = m->spi;
- t = m->transfers;
tmp = 0;
chipselect = 0;
status = 0;

- for (;;t++) {
+ list_for_each_entry (t, &m->transfers, link) {
if (bitbang->shutdown) {
status = -ESHUTDOWN;
break;
@@ -295,10 +294,6 @@
if (t->delay_usecs)
udelay(t->delay_usecs);

- tmp++;
- if (tmp >= m->n_transfer)
- break;
-
chipselect = !t->cs_change;
if (chipselect)
continue;
@@ -308,8 +303,8 @@
msleep(1);
}

- tmp = m->n_transfer - 1;
- tmp = m->transfers[tmp].cs_change;
+ if (t)
+ tmp = t->cs_change;

m->status = status;
m->complete(m->context);
diff -uNr --exclude='patches*' --exclude=.pc linux-2.6.orig/drivers/spi/spi.c linux-2.6/drivers/spi/spi.c
--- linux-2.6.orig/drivers/spi/spi.c 2005-12-23 13:46:16.000000000 +0300
+++ linux-2.6/drivers/spi/spi.c 2005-12-23 15:28:58.000000000 +0300
@@ -546,7 +546,7 @@
static DECLARE_MUTEX(lock);

int status;
- struct spi_message message;
+ DECLARE_SPI_MESSAGE(message);
struct spi_transfer x[2];
u8 *local_buf;

@@ -570,13 +570,13 @@
memcpy(local_buf, txbuf, n_tx);
x[0].tx_buf = local_buf;
x[0].len = n_tx;
+ list_add_tail(&x[0].link, &message.transfers);

x[1].rx_buf = local_buf + n_tx;
x[1].len = n_rx;
+ list_add_tail(&x[1].link, &message.transfers);

/* do the i/o */
- message.transfers = x;
- message.n_transfer = ARRAY_SIZE(x);
status = spi_sync(spi, &message);
if (status == 0) {
memcpy(rxbuf, x[1].rx_buf, n_rx);
diff -uNr --exclude='patches*' --exclude=.pc linux-2.6.orig/include/linux/spi/spi.h linux-2.6/include/linux/spi/spi.h
--- linux-2.6.orig/include/linux/spi/spi.h 2005-12-23 13:46:16.000000000 +0300
+++ linux-2.6/include/linux/spi/spi.h 2005-12-23 15:34:21.000000000 +0300
@@ -316,12 +316,13 @@

unsigned cs_change:1;
u16 delay_usecs;
+
+ struct list_head link;
};

/**
* struct spi_message - one multi-segment SPI transaction
* @transfers: the segements of the transaction
- * @n_transfer: how many segments
* @spi: SPI device to which the transaction is queued
* @is_dma_mapped: if true, the caller provided both dma and cpu virtual
* addresses for each transfer buffer
@@ -339,8 +340,7 @@
* insulate against future API updates.
*/
struct spi_message {
- struct spi_transfer *transfers;
- unsigned n_transfer;
+ struct list_head transfers;

struct spi_device *spi;

@@ -371,6 +371,9 @@
void *state;
};

+#define DECLARE_SPI_MESSAGE(mmm) struct spi_message mmm = \
+ { .transfers = LIST_HEAD_INIT((mmm).transfers), }
+
/* It's fine to embed message and transaction structures in other data
* structures so long as you don't free them while they're in use.
*/
@@ -383,8 +386,12 @@
+ ntrans * sizeof(struct spi_transfer),
flags);
if (m) {
- m->transfers = (void *)(m + 1);
- m->n_transfer = ntrans;
+ int i;
+ struct spi_transfer *t = (struct spi_transfer *)(m + 1);
+
+ INIT_LIST_HEAD(&m->transfers);
+ for (i = 0; i < ntrans; i++)
+ list_add_tail(&t[i].link, &m->transfers);
}
return m;
}
@@ -472,10 +479,9 @@
.len = len,
.cs_change = 0,
};
- struct spi_message m;
+ DECLARE_SPI_MESSAGE(m);

- m.transfers = &t;
- m.n_transfer = 1;
+ list_add_tail(&t.link, &m.transfers);
return spi_sync(spi, &m);
}

@@ -497,10 +503,9 @@
.len = len,
.cs_change = 0,
};
- struct spi_message m;
+ DECLARE_SPI_MESSAGE(m);

- m.transfers = &t;
- m.n_transfer = 1;
+ list_add_tail(&t.link, &m.transfers);
return spi_sync(spi, &m);
}

-
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