高通APQ8074 spi 接口配置
8074 平台含有两个BLSP(BAM Low-Speed Peripheral) ， 每一个BLSP含有两个QUP, 每一个QUP可以被配置为I2C， SPI, UART, UIM接口， BLSP是高通对于低速接口的一种管理方式。
每个QUP是和特定的引脚相关的, 如下图所示，比如下面的引脚是属于BLSP8的， 也就是第二个BLSP的第二个QUP,
注意这些引脚只能被配置到第二个BLSP的第2个QUP上，可以通过继续查看高通相关资料
QUP的中断相关信息
得到这些信息后，如果只是要将SPI配置成FIFO模式，而不是BAM模式，需要修改如下文件
diff --git a/arch/arm/boot/dts/msm8974.dtsi b/arch/arm/boot/dts/msm8974.dtsi
index 4178acf..649aa87 100644--- a/arch/arm/boot/dts/msm8974.dtsi+++ b/arch/arm/boot/dts/msm8974.dtsi@@ -20,6 +20,7 @@ aliases { spi0 = &spi_0; spi7 = &spi_7;+ spi8 = &spi_8; sdhc1 = &sdhc_1; /* SDC1 eMMC slot */ sdhc2 = &sdhc_2; /* SDC2 SD card slot */ sdhc3 = &sdhc_3; /* SDC3 SDIO slot */@@ -888,6 +889,27 @@ qcom,master-id = <86>; }; + spi_8: spi@f9964000 { + compatible = "qcom,spi-qup-v2";+ reg = <0xf9964000 0x1000>;+ interrupts = <0 102 0>;+ spi-max-frequency = <19200000>;+ #address-cells = <1>;+ #size-cells = <0>;+ qcom,gpio-clk = <&msmgpio 48 0>; /* CLK */+ qcom,gpio-miso = <&msmgpio 46 0>; /* MISO */+ qcom,gpio-mosi = <&msmgpio 45 0>; /* MOSI */+ qcom,gpio-cs0 = <&msmgpio 47 0>;++ qcom,master-id = <84>;++ spidev@0 { //Slave driver and CS ID+ compatible = "qcom,spi_name"; //Manufacture, and Mode+ reg = <0>; //Same as CS ID+ spi-max-frequency = <3200000>; //Max Frequency for Device+ };+ };+ qcom,clock-krait@f9016000 { compatible = "qcom,clock-krait-8974"; reg = <0xf9016000 0x20>,/*使能 spi驱动， 可以修改spidev.c的 compatible 把名字修改为device tree相同的名字，之后kernel会挂在这个设备到spi总线，dev目录下将会出现spidev8.0的设备节点*/
diff --git a/arch/arm/configs/msm8974_defconfig b/arch/arm/configs/msm8974_defconfig
index a12538a..74c51e6 100755--- a/arch/arm/configs/msm8974_defconfig+++ b/arch/arm/configs/msm8974_defconfig@@ -315,7 +315,7 @@ CONFIG_I2C_CHARDEV=y CONFIG_I2C_QUP=y CONFIG_SPI=y CONFIG_SPI_QUP=y-CONFIG_SPI_SPIDEV=m+CONFIG_SPI_SPIDEV=y CONFIG_SPMI=y CONFIG_SPMI_MSM_PMIC_ARB=y CONFIG_MSM_QPNP_INT=y修改gpio SPI属性，注意GPIO的function不要和已经注册的function 冲突
diff --git a/arch/arm/mach-msm/board-8974-gpiomux.c b/arch/arm/mach-msm/board-8974-gpiomux.c
index cec1a8f..6d67f18 100755--- a/arch/arm/mach-msm/board-8974-gpiomux.c+++ b/arch/arm/mach-msm/board-8974-gpiomux.c@@ -683,6 +683,35 @@ static struct msm_gpiomux_config msm_blsp_configs[] __initdata = { [GPIOMUX_SUSPENDED] = &gpio_suspend_config[0], }, },++ { + .gpio = 45, /* BLSP2 QUP1 SPI_DATA_MOSI */+ .settings = { + [GPIOMUX_ACTIVE] = &gpio_spi_config,+ [GPIOMUX_SUSPENDED] = &gpio_suspend_config[1],+ },+ },+ { + .gpio = 46, /* BLSP2 QUP1 SPI_DATA_MISO */+ .settings = { + [GPIOMUX_ACTIVE] = &gpio_spi_config,+ [GPIOMUX_SUSPENDED] = &gpio_suspend_config[1],+ },+ },+ { + .gpio = 48, /* BLSP2 QUP1 SPI_CLK */+ .settings = { + [GPIOMUX_ACTIVE] = &gpio_spi_config,+ [GPIOMUX_SUSPENDED] = &gpio_suspend_config[0],+ },+ },+ { + .gpio = 47, /* BLSP2 QUP1 SPI_CS0_N */+ .settings = { + [GPIOMUX_ACTIVE] = &gpio_spi_config,+ [GPIOMUX_SUSPENDED] = &gpio_suspend_config[0],+ },+ }, };diff --git a/arch/arm/mach-msm/clock-8974.c b/arch/arm/mach-msm/clock-8974.c
index 128a363..adff33a 100755--- a/arch/arm/mach-msm/clock-8974.c+++ b/arch/arm/mach-msm/clock-8974.c@@ -4967,7 +4967,8 @@ static struct clk_lookup msm_clocks_8974_common[] __initdata = { CLK_LOOKUP("core_clk", gcc_blsp2_qup1_i2c_apps_clk.c, ""), CLK_LOOKUP("core_clk", gcc_blsp2_qup1_spi_apps_clk.c, ""), CLK_LOOKUP("core_clk", gcc_blsp2_qup2_i2c_apps_clk.c, ""),- CLK_LOOKUP("core_clk", gcc_blsp2_qup2_spi_apps_clk.c, ""),+ CLK_LOOKUP("iface_clk", gcc_blsp2_ahb_clk.c, "f9964000.spi"),+ CLK_LOOKUP("core_clk", gcc_blsp2_qup2_spi_apps_clk.c, "f9964000.spi"), CLK_LOOKUP("core_clk", gcc_blsp2_qup3_i2c_apps_clk.c, ""), CLK_LOOKUP("core_clk", gcc_blsp2_qup3_spi_apps_clk.c, ""), CLK_LOOKUP("core_clk", gcc_blsp2_qup4_i2c_apps_clk.c, ""),最后注意下使能的spidev.c设备驱动，这个驱动也需要修改spi_qsd.c 保存实际传输数据长度的actual_lenght字段不会被赋值，需要对spidev.c文件进行少许的修改
diff --git a/drivers/spi/spidev.c b/drivers/spi/spidev.c
index aaf0265..efb7d07 100644--- a/drivers/spi/spidev.c+++ b/drivers/spi/spidev.c@@ -198,14 +204,14 @@ spidev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos)
mutex_lock(&spidev->buf_lock); status = spidev_sync_read(spidev, count);- if (status > 0) { + if (status >= 0) { unsigned long missing; - missing = copy_to_user(buf, spidev->buffer, status);- if (missing == status)+ missing = copy_to_user(buf, spidev->buffer, count);+ if (missing == count) status = -EFAULT; else- status = status - missing;+ status = count - missing; } mutex_unlock(&spidev->buf_lock);之后可以通过打开dev/spidev8.0文件进行SPI设备的读写测试，需要注意的是，如果你用dragonboard, 需要注意一下电平转换芯片的电压，一定要在PMIC中时能对应的电压。