| Message ID | 1224878939.4039.22.camel@galileo.recco.de (mailing list archive) |
|---|---|
| State | Rejected, archived |
| Headers | show |
On Fri, Oct 24, 2008 at 10:08:59PM +0200, Wolfgang Ocker wrote: > SPI slave devices require the specification of a chip select address. > This patch allows that specification using the gpios property. The reg > property remains supported. > > Signed-off-by: Wolfgang Ocker <weo@reccoware.de> > --- > > --- linux-2.6.27.3/drivers/of/of_spi.c.of_spi_gpio 2008-10-22 23:38:01.000000000 +0200 > +++ linux-2.6.27.3/drivers/of/of_spi.c.of_spi_cshigh 2008-10-24 21:36:39.000000000 +0200 [...] > --- linux-2.6.27.3/Documentation/powerpc/booting-without-of.txt.of_spi_gpio 2008-10-22 23:38:01.000000000 +0200 > +++ linux-2.6.27.3/Documentation/powerpc/booting-without-of.txt.of_spi_cshigh 2008-10-24 21:57:16.000000000 +0200 > @@ -1909,7 +1909,9 @@ platforms are moved over to use the flat > > SPI slave nodes must be children of the SPI master node and can > contain the following properties. > - - reg - (required) chip select address of device. > + - reg - chip select address of device. > + - gpios - chip select address of device (alternatively). > + one of reg and gpios is required. > - compatible - (required) name of SPI device following generic names > recommended practice > - spi-max-frequency - (required) Maximum SPI clocking speed of device in Hz > @@ -1936,7 +1938,7 @@ platforms are moved over to use the flat > codec@1 { > compatible = "ti,tlv320aic26"; > spi-max-frequency = <100000>; > - reg = <1>; > + gpios = <&GPIO1 3>; > }; > }; Close, but no cigar. Sorry. ;-) The bindings are fine as is, you don't need to change them. The scheme should look like this: spi-controller { #address-cells = <1>; #size-cells = <0>; /* two GPIOs, representing two chip selects: 0 and 1 */ gpios = <&pio 5 0 &pio 16 0>; mmc-slot@0 { reg = <0>; }; touchscreen@1 { reg = <1>; }; } Notice that "gpios" is spi-controller's property, not spi devices'. It is truly as hardware works, SPI controllers consists of two units: I/O, and chip-select machine. Most spi controllers don't have dedicated chip-select machines, so they use GPIOs. The spi controller driver should request all the specified gpios, and then work with chip select numbers. Something like this: struct spi_controller { int *gpios; unsigned int num_gpios; ... } int spi_set_chipselect(struct spi_controller *spi, int cs, int active) { /* * chip-select is not necessary if there is just one device on * the bus, so gpios = <> are not necessary either */ */ if (!spi->num_gpios) return 0; if (cs > spi->num_gpios) return -EINVAL; gpio_set_value(spi->gpios[cs], active); } ... unsigned int of_num_gpios(struct device_node *node) { unsigned int num = 0; while (gpio_is_valid(of_get_gpio(node, num))) num++; return num; } int spi_controller_probe(...) { spi_controller *spi; ... spi->num_gpios = of_num_gpios(node); if (spi->num_gpios) { int i = spi->num_gpios; spi->gpios = kzalloc(sizeof(int) * i, GFP_KERNEL); if (!spi->gpios) return -ENOMEM; do spi->gpios[i] = of_get_gpio(node, i); while (!(i--)); } ... }
On Fri, Oct 24, 2008 at 3:10 PM, Anton Vorontsov <avorontsov@ru.mvista.com> wrote: > On Fri, Oct 24, 2008 at 10:08:59PM +0200, Wolfgang Ocker wrote: >> SPI slave devices require the specification of a chip select address. >> This patch allows that specification using the gpios property. The reg >> property remains supported. >> >> Signed-off-by: Wolfgang Ocker <weo@reccoware.de> >> --- >> >> --- linux-2.6.27.3/drivers/of/of_spi.c.of_spi_gpio 2008-10-22 23:38:01.000000000 +0200 >> +++ linux-2.6.27.3/drivers/of/of_spi.c.of_spi_cshigh 2008-10-24 21:36:39.000000000 +0200 > [...] >> --- linux-2.6.27.3/Documentation/powerpc/booting-without-of.txt.of_spi_gpio 2008-10-22 23:38:01.000000000 +0200 >> +++ linux-2.6.27.3/Documentation/powerpc/booting-without-of.txt.of_spi_cshigh 2008-10-24 21:57:16.000000000 +0200 >> @@ -1936,7 +1938,7 @@ platforms are moved over to use the flat >> codec@1 { >> compatible = "ti,tlv320aic26"; >> spi-max-frequency = <100000>; >> - reg = <1>; >> + gpios = <&GPIO1 3>; >> }; >> }; > > Close, but no cigar. Sorry. ;-) The bindings are fine as is, you don't > need to change them. > > The scheme should look like this: > > spi-controller { > #address-cells = <1>; > #size-cells = <0>; > > /* two GPIOs, representing two chip selects: 0 and 1 */ > gpios = <&pio 5 0 &pio 16 0>; > > mmc-slot@0 { > reg = <0>; > }; > > touchscreen@1 { > reg = <1>; > }; > } > > Notice that "gpios" is spi-controller's property, not spi devices'. > It is truly as hardware works, SPI controllers consists of two units: > I/O, and chip-select machine. Most spi controllers don't have > dedicated chip-select machines, so they use GPIOs. FWIW, I 100% agree. g.
On Sat, 2008-10-25 at 01:10 +0400, Anton Vorontsov wrote: > On Fri, Oct 24, 2008 at 10:08:59PM +0200, Wolfgang Ocker wrote: > > SPI slave devices require the specification of a chip select address. > > This patch allows that specification using the gpios property. The reg > > property remains supported. > > Close, but no cigar. Sorry. ;-) The bindings are fine as is, you don't > need to change them. Oh, what a steep learning curve! Anyway, thank you for your guidance and patience! Looks like I have to adjust the SPI driver. Wolfgang
--- linux-2.6.27.3/drivers/of/of_spi.c.of_spi_gpio 2008-10-22 23:38:01.000000000 +0200 +++ linux-2.6.27.3/drivers/of/of_spi.c.of_spi_cshigh 2008-10-24 21:36:39.000000000 +0200 @@ -10,6 +10,7 @@ #include <linux/device.h> #include <linux/spi/spi.h> #include <linux/of_spi.h> +#include <linux/of_gpio.h> /** * of_register_spi_devices - Register child devices onto the SPI bus @@ -24,6 +25,7 @@ void of_register_spi_devices(struct spi_ struct spi_device *spi; struct device_node *nc; const u32 *prop; + int cs_addr; int rc; int len; @@ -48,13 +50,20 @@ void of_register_spi_devices(struct spi_ /* Device address */ prop = of_get_property(nc, "reg", &len); - if (!prop || len < sizeof(*prop)) { - dev_err(&master->dev, "%s has no 'reg' property\n", - nc->full_name); - spi_dev_put(spi); - continue; + if (prop && len >= sizeof(*prop)) { + cs_addr = *prop; + } + else { + cs_addr = of_get_gpio(nc, 0); + if (cs_addr < 0) { + dev_err(&master->dev, + "%s has no 'reg' nor gpios property\n", + nc->full_name); + spi_dev_put(spi); + continue; + } } - spi->chip_select = *prop; + spi->chip_select = cs_addr; /* Mode (clock phase/polarity/etc.) */ if (of_find_property(nc, "spi-cpha", NULL)) --- linux-2.6.27.3/Documentation/powerpc/booting-without-of.txt.of_spi_gpio 2008-10-22 23:38:01.000000000 +0200 +++ linux-2.6.27.3/Documentation/powerpc/booting-without-of.txt.of_spi_cshigh 2008-10-24 21:57:16.000000000 +0200 @@ -1909,7 +1909,9 @@ platforms are moved over to use the flat SPI slave nodes must be children of the SPI master node and can contain the following properties. - - reg - (required) chip select address of device. + - reg - chip select address of device. + - gpios - chip select address of device (alternatively). + one of reg and gpios is required. - compatible - (required) name of SPI device following generic names recommended practice - spi-max-frequency - (required) Maximum SPI clocking speed of device in Hz @@ -1936,7 +1938,7 @@ platforms are moved over to use the flat codec@1 { compatible = "ti,tlv320aic26"; spi-max-frequency = <100000>; - reg = <1>; + gpios = <&GPIO1 3>; }; };
SPI slave devices require the specification of a chip select address. This patch allows that specification using the gpios property. The reg property remains supported. Signed-off-by: Wolfgang Ocker <weo@reccoware.de> ---