最近整理的一些msm8909平台英文文档4 - i2c_function_of_msm8909

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本文介绍了如何在MSM8909平台上配置QUP核心作为I2C设备的方法，包括创建设备树节点、设置时钟、配置GPIO等步骤，并提供了快速验证I2C总线是否正常工作的指导。

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Introduction
The QUP provides a general purpose data path engine support multiple mini cores. Each minicore implements protocol-specific logic. The common FIFOs provide a consistent system IO and system DMA model across widely varying external interface types. For example, one pair of FIFO can support SPI and I2C MiniCores independently.

Currently supported MiniCores
SPI
I2C

I2C Core:
Support I2C Standard (100 kHz), and Fast (400 kHz)
Key features added for MSM8909:
BAM integration
Support TAG (version 2)

QUP base address for QUPs:
In order to match the labeling of software interface manual, each QUP will be identified by BLSP core and QUP core (0 - 5). In hardware design documents, BLSPs are identified as BLSP[1:6]

BLSP hardware ID QUP core physical address (QUP_BASE_ADDRESS):
BLSP BLSP 1 QUP 0 0x78B5000
BLSP BLSP 1 QUP 1 0x78B6000
BLSP BLSP 1 QUP 2 0x78B7000
BLSP BLSP 1 QUP 3 0x78B8000
BLSP BLSP 1 QUP 4 0x78B9000
BLSP BLSP 1 QUP 5 0x78BA000

IRQs for QUPs:
BLSP BLSP 1 QUP 0 95
BLSP BLSP 1 QUP 1 96
BLSP BLSP 1 QUP 2 97
BLSP BLSP 1 QUP 3 98
BLSP BLSP 1 QUP 4 99
BLSP BLSP 1 QUP 5 100

Configure QUP core as I2C in kernel
This section describes steps necessary to configure any of the six QUP cores available in MSM8909 to configure and use as a I2C device. By default QTI already preconfigures BLSP1_QUP5 as I2C.

See kernel/arch/arm/boot/dts/qcom/sim8909_evb103-msm8909.dtsi for more details. Following example shows how to configure BLSP1_QUP0 as I2C.

1. Create device tree node:
User can use kernel/arch/arm/boot/sim8909_evb103-msm8909.dtsi

	i2c_1: i2c@78b5000 { /* BLSP1 QUP1 */
		compatible = "qcom,i2c-msm-v2";
		#address-cells = <1>;
		#size-cells = <0>;
		reg-names = "qup_phys_addr";
		reg = <0x78b5000 0x1000>;
		interrupt-names = "qup_irq";
		interrupts = <0 95 0>;
		clocks = <&clock_gcc clk_gcc_blsp1_ahb_clk>,
		         <&clock_gcc clk_gcc_blsp1_qup1_i2c_apps_clk>;
		clock-names = "iface_clk", "core_clk";
		qcom,clk-freq-out = <100000>;
		qcom,clk-freq-in  = <19200000>;
		pinctrl-names = "i2c_active", "i2c_sleep";
		pinctrl-0 = <&i2c_1_active>;
		pinctrl-1 = <&i2c_1_sleep>;
		qcom,noise-rjct-scl = <0>;
		qcom,noise-rjct-sda = <0>;
		dmas = <&dma_blsp1 4 64 0x20000020 0x20>,
			<&dma_blsp1 5  32 0x20000020 0x20>;
		dma-names = "tx", "rx";
		qcom,master-id = <86>;
	};

For latest detail plese follow :
kernel/Documentation/devicetree/bindings/i2c/i2c-qup.txt

Set up clocks:
kernel/drivers/clk/qcom/clock-gcc-8909.c

static struct branch_clk gcc_blsp1_qup1_i2c_apps_clk = {
	.cbcr_reg = BLSP1_QUP1_I2C_APPS_CBCR,
	.has_sibling = 0,
	.base = &virt_bases[GCC_BASE],
	.c = {
		.dbg_name = "gcc_blsp1_qup1_i2c_apps_clk",
		.parent = &blsp1_qup1_i2c_apps_clk_src.c,
		.ops = &clk_ops_branch,
		CLK_INIT(gcc_blsp1_qup1_i2c_apps_clk.c),
	},
};

static struct rcg_clk blsp1_qup1_i2c_apps_clk_src = {
	.cmd_rcgr_reg = BLSP1_QUP1_I2C_APPS_CMD_RCGR,
	.set_rate = set_rate_hid,
	.freq_tbl = ftbl_gcc_blsp1_qup1_6_i2c_apps_clk,
	.current_freq = &rcg_dummy_freq,
	.base = &virt_bases[GCC_BASE],
	.c = {
		.dbg_name = "blsp1_qup1_i2c_apps_clk_src",
		.ops = &clk_ops_rcg,
		VDD_DIG_FMAX_MAP1(LOWER, 50000000),
		CLK_INIT(blsp1_qup1_i2c_apps_clk_src.c),
	},
};

2. Setup GPIOs:
kernel/arch/arm/boot/sim8909_evb103-msm8909-pinctrl.dtsi

pmx_i2c_1 {
                        /* CLK, DATA */
			qcom,pins = <&gp 6>, <&gp 7>;
			qcom,num-grp-pins = <2>;
			qcom,pin-func = <3>;
			label = "pmx_i2c_1";


			i2c_1_active: i2c_1_active {
				drive-strength = <2>; /* 2 MA */
				bias-disable = <0>; /* No PULL */
			};


			i2c_1_sleep: i2c_1_sleep {
				drive-strength = <2>; /* 2 MA */
				bias-pull-down; /* PULL DOWN */
			};
		};

Quick verification:
This section describes how to quickly verify I2C bus.
Check if the bus is registered. If you have entered all the information correctly, then you should see I2C bus.
registered under /dev/i2c-#. Where cell-index would match the bus #.
adb shell --> Get adb shell
cd /dev/
ls i2c* --> to List all the I2C buses

For example:
root@android:/dev # ls i2c*
ls i2c*
i2c-0

i2c-1