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path: root/drivers/spi/spi_butterfly.c
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Diffstat (limited to 'drivers/spi/spi_butterfly.c')
-rw-r--r--drivers/spi/spi_butterfly.c36
1 files changed, 17 insertions, 19 deletions
diff --git a/drivers/spi/spi_butterfly.c b/drivers/spi/spi_butterfly.c
index 79a3c59..ff9e5fa 100644
--- a/drivers/spi/spi_butterfly.c
+++ b/drivers/spi/spi_butterfly.c
@@ -163,21 +163,20 @@ static void butterfly_chipselect(struct spi_device *spi, int value)
struct butterfly *pp = spidev_to_pp(spi);
/* set default clock polarity */
- if (value)
+ if (value != BITBANG_CS_INACTIVE)
setsck(spi, spi->mode & SPI_CPOL);
/* no chipselect on this USI link config */
if (is_usidev(spi))
return;
- /* here, value == "activate or not" */
-
- /* most PARPORT_CONTROL_* bits are negated */
+ /* here, value == "activate or not";
+ * most PARPORT_CONTROL_* bits are negated, so we must
+ * morph it to value == "bit value to write in control register"
+ */
if (spi_cs_bit == PARPORT_CONTROL_INIT)
value = !value;
- /* here, value == "bit value to write in control register" */
-
parport_frob_control(pp->port, spi_cs_bit, value ? spi_cs_bit : 0);
}
@@ -202,7 +201,9 @@ butterfly_txrx_word_mode0(struct spi_device *spi,
/* override default partitioning with cmdlinepart */
static struct mtd_partition partitions[] = { {
- /* JFFS2 wants partitions of 4*N blocks for this device ... */
+ /* JFFS2 wants partitions of 4*N blocks for this device,
+ * so sectors 0 and 1 can't be partitions by themselves.
+ */
/* sector 0 = 8 pages * 264 bytes/page (1 block)
* sector 1 = 248 pages * 264 bytes/page
@@ -316,8 +317,9 @@ static void butterfly_attach(struct parport *p)
if (status < 0)
goto clean2;
- /* Bus 1 lets us talk to at45db041b (firmware disables AVR)
- * or AVR (firmware resets at45, acts as spi slave)
+ /* Bus 1 lets us talk to at45db041b (firmware disables AVR SPI), AVR
+ * (firmware resets at45, acts as spi slave) or neither (we ignore
+ * both, AVR uses AT45). Here we expect firmware for the first option.
*/
pp->info[0].max_speed_hz = 15 * 1000 * 1000;
strcpy(pp->info[0].modalias, "mtd_dataflash");
@@ -330,7 +332,9 @@ static void butterfly_attach(struct parport *p)
pp->dataflash->dev.bus_id);
#ifdef HAVE_USI
- /* even more custom AVR firmware */
+ /* Bus 2 is only for talking to the AVR, and it can work no
+ * matter who masters bus 1; needs appropriate AVR firmware.
+ */
pp->info[1].max_speed_hz = 10 /* ?? */ * 1000 * 1000;
strcpy(pp->info[1].modalias, "butterfly");
// pp->info[1].platform_data = ... TBD ... ;
@@ -378,13 +382,8 @@ static void butterfly_detach(struct parport *p)
pp = butterfly;
butterfly = NULL;
-#ifdef HAVE_USI
- spi_unregister_device(pp->butterfly);
- pp->butterfly = NULL;
-#endif
- spi_unregister_device(pp->dataflash);
- pp->dataflash = NULL;
-
+ /* stop() unregisters child devices too */
+ pdev = to_platform_device(pp->bitbang.master->cdev.dev);
status = spi_bitbang_stop(&pp->bitbang);
/* turn off VCC */
@@ -394,8 +393,6 @@ static void butterfly_detach(struct parport *p)
parport_release(pp->pd);
parport_unregister_device(pp->pd);
- pdev = to_platform_device(pp->bitbang.master->cdev.dev);
-
(void) spi_master_put(pp->bitbang.master);
platform_device_unregister(pdev);
@@ -420,4 +417,5 @@ static void __exit butterfly_exit(void)
}
module_exit(butterfly_exit);
+MODULE_DESCRIPTION("Parport Adapter driver for AVR Butterfly");
MODULE_LICENSE("GPL");