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[PATCH] SPI: spi_butterfly, restore lost deltas
This resolves some minor version skew glitches that accumulated for the AVR Butterfly adapter driver, which caused among other things the existence of a duplicate Kconfig entry. Most of it boils down to comment updates, but in one case it removes some now-superfluous code that would be better if not copied into other controller-level drivers. Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
This commit is contained in:
David Brownell
Greg Kroah-Hartman
parent
022f7b07bf
commit
9c1da3cb46
@ -12,13 +12,20 @@ You can make this adapter from an old printer cable and solder things
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directly to the Butterfly. Or (if you have the parts and skills) you
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can come up with something fancier, providing ciruit protection to the
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Butterfly and the printer port, or with a better power supply than two
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signal pins from the printer port.
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signal pins from the printer port. Or for that matter, you can use
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similar cables to talk to many AVR boards, even a breadboard.
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This is more powerful than "ISP programming" cables since it lets kernel
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SPI protocol drivers interact with the AVR, and could even let the AVR
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issue interrupts to them. Later, your protocol driver should work
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easily with a "real SPI controller", instead of this bitbanger.
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The first cable connections will hook Linux up to one SPI bus, with the
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AVR and a DataFlash chip; and to the AVR reset line. This is all you
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need to reflash the firmware, and the pins are the standard Atmel "ISP"
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connector pins (used also on non-Butterfly AVR boards).
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connector pins (used also on non-Butterfly AVR boards). On the parport
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side this is like "sp12" programming cables.
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Signal Butterfly Parport (DB-25)
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------ --------- ---------------
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@ -40,10 +47,14 @@ by clearing PORTB.[0-3]); (b) configure the mtd_dataflash driver; and
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SELECT = J400.PB0/nSS = pin 17/C3,nSELECT
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GND = J400.GND = pin 24/GND
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The "USI" controller, using J405, can be used for a second SPI bus. That
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would let you talk to the AVR over SPI, running firmware that makes it act
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as an SPI slave, while letting either Linux or the AVR use the DataFlash.
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There are plenty of spare parport pins to wire this one up, such as:
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Or you could flash firmware making the AVR into an SPI slave (keeping the
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DataFlash in reset) and tweak the spi_butterfly driver to make it bind to
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the driver for your custom SPI-based protocol.
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The "USI" controller, using J405, can also be used for a second SPI bus.
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That would let you talk to the AVR using custom SPI-with-USI firmware,
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while letting either Linux or the AVR use the DataFlash. There are plenty
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of spare parport pins to wire this one up, such as:
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Signal Butterfly Parport (DB-25)
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------ --------- ---------------
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@ -75,16 +75,6 @@ config SPI_BUTTERFLY
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inexpensive battery powered microcontroller evaluation board.
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This same cable can be used to flash new firmware.
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config SPI_BUTTERFLY
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tristate "Parallel port adapter for AVR Butterfly (DEVELOPMENT)"
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depends on SPI_MASTER && PARPORT && EXPERIMENTAL
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select SPI_BITBANG
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help
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This uses a custom parallel port cable to connect to an AVR
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Butterfly <http://www.atmel.com/products/avr/butterfly>, an
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inexpensive battery powered microcontroller evaluation board.
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This same cable can be used to flash new firmware.
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#
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# Add new SPI master controllers in alphabetical order above this line
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#
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@ -163,21 +163,20 @@ static void butterfly_chipselect(struct spi_device *spi, int value)
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struct butterfly *pp = spidev_to_pp(spi);
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/* set default clock polarity */
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if (value)
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if (value != BITBANG_CS_INACTIVE)
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setsck(spi, spi->mode & SPI_CPOL);
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/* no chipselect on this USI link config */
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if (is_usidev(spi))
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return;
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/* here, value == "activate or not" */
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/* most PARPORT_CONTROL_* bits are negated */
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/* here, value == "activate or not";
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* most PARPORT_CONTROL_* bits are negated, so we must
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* morph it to value == "bit value to write in control register"
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*/
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if (spi_cs_bit == PARPORT_CONTROL_INIT)
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value = !value;
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/* here, value == "bit value to write in control register" */
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parport_frob_control(pp->port, spi_cs_bit, value ? spi_cs_bit : 0);
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}
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@ -202,7 +201,9 @@ butterfly_txrx_word_mode0(struct spi_device *spi,
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/* override default partitioning with cmdlinepart */
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static struct mtd_partition partitions[] = { {
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/* JFFS2 wants partitions of 4*N blocks for this device ... */
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/* JFFS2 wants partitions of 4*N blocks for this device,
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* so sectors 0 and 1 can't be partitions by themselves.
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*/
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/* sector 0 = 8 pages * 264 bytes/page (1 block)
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* sector 1 = 248 pages * 264 bytes/page
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@ -316,8 +317,9 @@ static void butterfly_attach(struct parport *p)
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if (status < 0)
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goto clean2;
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/* Bus 1 lets us talk to at45db041b (firmware disables AVR)
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* or AVR (firmware resets at45, acts as spi slave)
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/* Bus 1 lets us talk to at45db041b (firmware disables AVR SPI), AVR
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* (firmware resets at45, acts as spi slave) or neither (we ignore
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* both, AVR uses AT45). Here we expect firmware for the first option.
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*/
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pp->info[0].max_speed_hz = 15 * 1000 * 1000;
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strcpy(pp->info[0].modalias, "mtd_dataflash");
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@ -330,7 +332,9 @@ static void butterfly_attach(struct parport *p)
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pp->dataflash->dev.bus_id);
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#ifdef HAVE_USI
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/* even more custom AVR firmware */
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/* Bus 2 is only for talking to the AVR, and it can work no
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* matter who masters bus 1; needs appropriate AVR firmware.
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*/
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pp->info[1].max_speed_hz = 10 /* ?? */ * 1000 * 1000;
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strcpy(pp->info[1].modalias, "butterfly");
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// pp->info[1].platform_data = ... TBD ... ;
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@ -378,13 +382,8 @@ static void butterfly_detach(struct parport *p)
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pp = butterfly;
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butterfly = NULL;
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#ifdef HAVE_USI
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spi_unregister_device(pp->butterfly);
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pp->butterfly = NULL;
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#endif
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spi_unregister_device(pp->dataflash);
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pp->dataflash = NULL;
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/* stop() unregisters child devices too */
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pdev = to_platform_device(pp->bitbang.master->cdev.dev);
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status = spi_bitbang_stop(&pp->bitbang);
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/* turn off VCC */
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@ -394,8 +393,6 @@ static void butterfly_detach(struct parport *p)
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parport_release(pp->pd);
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parport_unregister_device(pp->pd);
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pdev = to_platform_device(pp->bitbang.master->cdev.dev);
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(void) spi_master_put(pp->bitbang.master);
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platform_device_unregister(pdev);
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@ -420,4 +417,5 @@ static void __exit butterfly_exit(void)
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}
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module_exit(butterfly_exit);
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MODULE_DESCRIPTION("Parport Adapter driver for AVR Butterfly");
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MODULE_LICENSE("GPL");
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