Rockchip SPI 功能特点

SPI （serial peripheral interface），以下是 linux 4.4 spi 驱动支持的一些特性︰

默认采用摩托罗拉 SPI 协议
支持 8 位和 16 位
软件可编程时钟频率和传输速率高达 50MHz
支持 SPI 4 种传输模式配置
每个 SPI 控制器支持一个到两个片选
除以上支持，linux 4.19 新增以下特性：
框架支持 slave 和 master 两种模式

代码路径

内核配置

DTS 节点配置

spi1: spi@fe620000 {compatible = "rockchip,rk3066-spi";reg = <0x0 0xfe620000 0x0 0x1000>;interrupts = <0 104 4>;#address-cells = <1>;#size-cells = <0>;clocks = <&cru 340>, <&cru 339>;clock-names = "spiclk", "apb_pclk";dmas = <&dmac0 22>, <&dmac0 23>;dma-names = "tx", "rx";pinctrl-names = "default", "high_speed";pinctrl-0 = <&spi1m0_cs0 &spi1m0_cs1 &spi1m0_pins>;pinctrl-1 = <&spi1m0_cs0 &spi1m0_cs1 &spi1m0_pins_hs>;status = "disabled";
};

&spi1 ：引用spi 控制器节点
clocks：指定 SPI sclk，可以通过查看 dtsi 中命名为 spiclk 的时钟
dmas 、dma-names ：使能DMA模式，一般通讯字节少于32字节的不建议用，dtsi 中默认设定，可通过置空赋值去掉使能;

spi 读写操作

对 spi 读写操作请参考 include/linux/spi/spi.h，以下简单列出几个：

spi_write

/*** spi_write - SPI synchronous write* @spi: device to which data will be written* @buf: data buffer* @len: data buffer size* Context: can sleep** This function writes the buffer @buf.* Callable only from contexts that can sleep.** Return: zero on success, else a negative error code.*/
static inline int
spi_write(struct spi_device *spi, const void *buf, size_t len)
{struct spi_transfer    t = {.tx_buf       = buf,.len     = len,};return spi_sync_transfer(spi, &t, 1);
}

spi_read

/*** spi_read - SPI synchronous read* @spi: device from which data will be read* @buf: data buffer* @len: data buffer size* Context: can sleep** This function reads the buffer @buf.* Callable only from contexts that can sleep.** Return: zero on success, else a negative error code.*/
static inline int
spi_read(struct spi_device *spi, void *buf, size_t len)
{struct spi_transfer    t = {.rx_buf       = buf,.len     = len,};return spi_sync_transfer(spi, &t, 1);
}

spi_sync_transfer

/*** spi_sync_transfer - synchronous SPI data transfer* @spi: device with which data will be exchanged* @xfers: An array of spi_transfers* @num_xfers: Number of items in the xfer array* Context: can sleep** Does a synchronous SPI data transfer of the given spi_transfer array.** For more specific semantics see spi_sync().** Return: Return: zero on success, else a negative error code.*/
static inline int
spi_sync_transfer(struct spi_device *spi, struct spi_transfer *xfers,unsigned int num_xfers)
{struct spi_message msg;spi_message_init_with_transfers(&msg, xfers, num_xfers);return spi_sync(spi, &msg);
}

当然也可以自己封装，以下也简单列出几个

spidev_sync_write

static inline ssize_t
spidev_sync_write(struct spidev_data *spidev, size_t len)
{int status;char cmd[1] = {PAGE_PROGRAM};unsigned char addr[3];struct spi_transfer c[] = {{.tx_buf = cmd,.len = ARRAY_SIZE(cmd),},{.tx_buf = addr,.len = ARRAY_SIZE(addr),},};struct spi_transfer t = {.tx_buf       = spidev->tx_buffer,.len        = len,.speed_hz    = spidev->speed_hz,};struct spi_message m;addr[0] = (unsigned char)((spidev->cur_addr & 0xff0000) >> 16);addr[1] = (unsigned char)((spidev->cur_addr & 0xff00) >> 8);addr[2] = (unsigned char)(spidev->cur_addr & 0xff);rs_spi_w25x_write_enable(spidev->spi);spi_message_init(&m);spi_message_add_tail(&c[0], &m);spi_message_add_tail(&c[1], &m);spi_message_add_tail(&t, &m);status = spidev_sync(spidev, &m);rs_spi_w25x_wait_ready(spidev->spi);return status;
}

spidev_sync_read

static inline ssize_t
spidev_sync_read(struct spidev_data *spidev, size_t len)
{int status;char cmd[] = {READ_DATA};unsigned char addr[3];struct spi_transfer t[] = {{.tx_buf = cmd,.len = ARRAY_SIZE(cmd),.speed_hz = spidev->speed_hz,},{.tx_buf = addr,.len = ARRAY_SIZE(addr),},{.rx_buf     = spidev->rx_buffer,.len        = len,.speed_hz    = spidev->speed_hz,}};struct spi_message    m;addr[0] = (unsigned char)((spidev->cur_addr & 0xff0000) >> 16);addr[1] = (unsigned char)((spidev->cur_addr & 0xff00) >> 8);addr[2] = (unsigned char)(spidev->cur_addr & 0xff);spi_message_init(&m);spi_message_add_tail(&t[0], &m);spi_message_add_tail(&t[1], &m);spi_message_add_tail(&t[2], &m);status = spidev_sync(spidev, &m);rs_spi_w25x_wait_ready(spidev->spi);return status;
}

例子

&spi1 {status = "okay" ;spi_test@00 {status = "okay";compatible = "rockchip,test";reg = <0x00>;spi-max-frequency = <24000000>; /*spi clk输出的时钟频率，不超过
50M */spi-lsb-first;  /* IO 先传输 lsb8*/spi-cpha;       /*SPI mode: CPHA = 1,不配置则为 0*/spi-cpol;       /*SPI mode: CPOL = 1,不配置则为 0*/
};

spiclk assigned-clock-rates 和 spi-max-frequency 的配置说明：

spi-max-frequency 是 SPI 的输出时钟，由 SPI 工作时钟 spiclk assigned-clock-rates 内部分频后输出，由于内部至少 2 分频，所以关系是 spiclk assigned-clock-rates >= 2*spi-max-frequency；
假定需要 50MHz 的 SPI IO 速率，可以考虑配置（记住内部分频为偶数分频）spi_clk assigned-clockrates = <100000000>，spi-max-frequency = <50000000>，即工作时钟 100 MHz（PLL 分频到一个不大于 100MHz 但最接近的值），然后内部二分频最终 IO 接近 50 MHz；
spiclk assigned-clock-rates 不要低于 24M，否则可能有问题；
如果需要配置 spi-cpha 的话，要求 spiclk assigned-clock-rates <= 6M, 1M <= spi-max-frequency >=3M

cs-gpios 支持

可以通过 spi-bus 的 cs-gpios 属性来实现 gpio 模拟 cs 以扩展 SPI 片选信号

Optional properties (master mode only):
- cs-gpios    - gpios chip select.
- num-cs      - total number of chipselects.If cs-gpios is used the number of chip selects will be increased automatically
with max(cs-gpios > hw cs).So if for example the controller has 2 CS lines, and the cs-gpios
property looks like this:cs-gpios = <&gpio1 0 0>, <0>, <&gpio1 1 0>, <&gpio1 2 0>;Then it should be configured so that num_chipselect = 4 with the
following mapping:cs0 : &gpio1 0 0
cs1 : native
cs2 : &gpio1 1 0
cs3 : &gpio1 2 0

设备驱动注册

static int spi_test_probe(struct spi_device *spi)
{int ret;int id = 0;if(!spi)return -ENOMEM;spi->bits_per_word= 8;ret= spi_setup(spi);if(ret < 0) {dev_err(&spi->dev,"ERR: fail to setup spi\n");return-1;} return ret;
} static int spi_test_remove(struct spi_device *spi)
{printk("%s\n",__func__);return 0;
}static const struct of_device_id spi_test_dt_match[]= {{.compatible = "rockchip,test",}.{},
};
MODULE_DEVICE_TABLE(of,spi_test_dt_match);static struct spi_driver spi_test_driver = {.driver = {.name = "spi_test",.owner = THIS_MODULE,.of_match_table = of_match_ptr(spi_test_dt_match),},.probe = spi_test_probe,.remove = spi_test_remove,
};static int __init spi_test_init(void)
{int ret = 0;ret = spi_register_driver(&spi_test_driver);return ret;
}
device_initcall(spi_test_init);static void __exit spi_test_exit(void)
{return spi_unregister_driver(&spi_test_driver);
}
module_exit(spi_test_exit);

具体的使用可以参考：https://blog.csdn.net/qq_29890089/article/details/121230149

RK356X SPI 使用相关推荐

stc15w404as引脚图_STC15F2K6S2与stc15w404AS的spi通讯
#include/*********************************位定义***********************************/ #define uchar unsi ...
I2C和SPI总线优缺点对比
IIC vs SPI现今,在低端数字通信应用领域,我们随处可见IIC (Inter-Integrated Circuit) 和 SPI (Serial Peripheral Interface)的身影 ...
Java中的ClassLoader和SPI机制
深入探讨 Java 类加载器成富是著名的Java专家,在IBM技术网站发表很多Java好文,也有著作. 线程上下文类加载器线程上下文类加载器(context class loader)是从 JDK ...
Java的SPI机制
Dubbo等框架使用到必须掌握. java.sql.Driver 是 Spi,com.mysql.jdbc.Driver 是 Spi 实现,其它的都是 Api. package org.hadoop. ...
linux spi双机通信,【转】STM32 SPI双机通信（主从全双工）
欢迎大家测试 u8 SPI1_ReadByte(u8 TxData) { u8 retry=0; // while((SPI1->SR&1<<1)==0)//等待发送区空 / ...
JDK/Dubbo/Spring 三种 SPI 机制，谁更好？
点击关注公众号,Java干货及时送达来源:juejin.cn/post/6950266942875779108 SPI 全称为 Service Provider Interface,是一种服务发现机 ...
通讯波形记录——I2S、I2C、Uart、SPI
SPI波形设置: UART I2S 扩展: I2S有3个主要信号: 1. SCLK:串行时钟,也叫位时钟(BCLK),即对应数字音频的每一位数据,SCLK都有1个脉冲.SCLK的频率=2×采样频率 ...
SPI flash配置
配置表中预先配好了一些,我们用到什么SPI就需要添加相应的spi配置参数 spi flash name jedec_id ext_id block_size chip_size clk chip se ...
spi nor flash使用汇总
Overview SPI flash, 分为spi flash, DUAL spi flash, QUAD spi flash, 3-wire spi, 4-wire spi, 6-wire spi. ...
c语言spi发送12位数据,【51单片机】普通I/O口模拟SPI口C语言程序
该楼层疑似违规已被系统折叠隐藏此楼查看此楼 89C51系列单片机都不带SPI口,所在在这种情况下,我们可以模拟SPI口来现实我们要的功能,程序如下: //---------------------- ...

RK356X SPI 使用