Enable SPI CS0 (spidev5.0) on Intel Edison

edison-force-spidev.patch

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 82b8dca..e1a4789 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -457,6 +457,9 @@ config X86_INTEL_MID
 	  nor standard legacy replacement devices/features. e.g. It does not
 	  contain i8259, i8254, HPET, legacy BIOS, most of the io ports.
 
+config INTEL_MID_FORCE_SPIDEV
+	bool "Force spidev"
+
 config X86_MDFLD
 	bool "Medfield MID platform"
 	depends on X86_INTEL_MID
diff --git a/arch/x86/configs/i386_edison_defconfig b/arch/x86/configs/i386_edison_defconfig
index 4e68b91..da0f0a0 100644
--- a/arch/x86/configs/i386_edison_defconfig
+++ b/arch/x86/configs/i386_edison_defconfig
@@ -322,6 +322,7 @@ CONFIG_X86_EXTENDED_PLATFORM=y
 # CONFIG_X86_GOLDFISH is not set
 CONFIG_X86_WANT_INTEL_MID=y
 CONFIG_X86_INTEL_MID=y
+CONFIG_INTEL_MID_FORCE_SPIDEV=y
 # CONFIG_X86_MDFLD is not set
 CONFIG_ATOM_SOC_POWER=y
 # CONFIG_REMOVEME_INTEL_ATOM_MDFLD_POWER is not set
diff --git a/arch/x86/platform/intel-mid/device_libs/platform_ads7955.c b/arch/x86/platform/intel-mid/device_libs/platform_ads7955.c
index c0d07aa..b0daafa 100644
--- a/arch/x86/platform/intel-mid/device_libs/platform_ads7955.c
+++ b/arch/x86/platform/intel-mid/device_libs/platform_ads7955.c
@@ -17,13 +17,53 @@
 #include <asm/intel-mid.h>
 #include "platform_ads7955.h"
 
+#ifdef CONFIG_INTEL_MID_FORCE_SPIDEV
+static void tng_ssp_spi_cs_control(u32 command);
+static void tng_ssp_spi_platform_pinmux(void);
+
+static int tng_ssp_spi2_FS_gpio = 110;
+#endif
+
 static struct intel_mid_ssp_spi_chip chip = {
 	.burst_size = DFLT_FIFO_BURST_SIZE,
 	.timeout = DFLT_TIMEOUT_VAL,
+#ifdef CONFIG_INTEL_MID_FORCE_SPIDEV
+	/* SPI DMA is currently usable on Tangier */
+	.dma_enabled = true,
+	.cs_control = tng_ssp_spi_cs_control,
+	.platform_pinmux = tng_ssp_spi_platform_pinmux,
+#else
 	/* SPI DMA is current not usable on Tangier */
 	.dma_enabled = false,
+#endif
 };
 
+#ifdef CONFIG_INTEL_MID_FORCE_SPIDEV
+static void tng_ssp_spi_cs_control(u32 command)
+{
+	gpio_set_value(tng_ssp_spi2_FS_gpio, (command != 0) ? 1 : 0);
+}
+
+static void tng_ssp_spi_platform_pinmux(void)
+{
+	int err;
+	int saved_muxing;
+	/* Request Chip Select gpios */
+	saved_muxing = gpio_get_alt(tng_ssp_spi2_FS_gpio);
+
+	lnw_gpio_set_alt(tng_ssp_spi2_FS_gpio, LNW_GPIO);
+	err = gpio_request_one(tng_ssp_spi2_FS_gpio,
+			GPIOF_DIR_OUT|GPIOF_INIT_HIGH, "Minibreakout FS0");
+	if (err) {
+		pr_err("%s: unable to get Chip Select GPIO,\
+				fallback to legacy CS mode \n", __func__);
+		lnw_gpio_set_alt(tng_ssp_spi2_FS_gpio, saved_muxing);
+		chip.cs_control = NULL;
+		chip.platform_pinmux = NULL;
+	}
+}
+#endif
+
 void __init *ads7955_platform_data(void *info)
 {
 	struct spi_board_info *spi_info = info;
@@ -32,6 +72,9 @@ void __init *ads7955_platform_data(void *info)
 
 	spi_info->controller_data = &chip;
 	spi_info->bus_num = FORCE_SPI_BUS_NUM;
+#ifdef CONFIG_INTEL_MID_FORCE_SPIDEV
+	spi_info->chip_select = FORCE_CHIP_SELECT;
+#endif
 
 	return NULL;
 }
diff --git a/arch/x86/platform/intel-mid/intel_mid_sfi.c b/arch/x86/platform/intel-mid/intel_mid_sfi.c
index f73b84e..429c1bf 100644
--- a/arch/x86/platform/intel-mid/intel_mid_sfi.c
+++ b/arch/x86/platform/intel-mid/intel_mid_sfi.c
@@ -375,6 +375,12 @@ static void __init sfi_handle_spi_dev(struct sfi_device_table_entry *pentry,
 
 	memset(&spi_info, 0, sizeof(spi_info));
 	strncpy(spi_info.modalias, pentry->name, SFI_NAME_LEN);
+#ifdef CONFIG_INTEL_MID_FORCE_SPIDEV
+	if (strncmp(spi_info.modalias, "ads7955", SFI_NAME_LEN) == 0) {
+		pr_info("Use ads7955 as spidev\n");
+		strncpy(spi_info.modalias, "spidev", SFI_NAME_LEN);
+	}
+#endif
 	spi_info.irq = ((pentry->irq == (u8)0xff) ? 0 : pentry->irq);
 	spi_info.bus_num = pentry->host_num;
 	spi_info.chip_select = pentry->addr;

@ecc1, I started doing such for upstream, but realized, that is waste of time since we are working on open connected board. And thus I postponed such until we will have ACPI in place. Regarding to the topic, the idea as I can see just to override ADS7955 file to mimic spidev. Have you enabled config option for that?

UPDATE. Have got an ACPI excerpt to enable it. Though don't know how to test it yet. (It required couple of patches to the driver still)