MT6573 YuSu SPI Customer Document [1.0 ed.]

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Yusu SPI Customer Document

Version: Release date:

1.0 2011-02-18

© 2008 - 2011 MediaTek Inc. This document contains information that is proprietary to MediaTek Inc. Unauthorized reproduction or disclosure of this information in whole or in part is strictly prohibited.

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Specifications are subject to change without notice.

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Document Revision History

Revision

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1．0

Date

Author

2011-02-18

Cindy Zhang

MediaTek Confidential

Description Initial

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This document contains information that is proprietary to MediaTek Inc. Unauthorized reproduction or disclosure of this information in whole or in part is strictly prohibited.

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Table of Contents

Document Revision History .................................................................................................................. 2 Table of Contents................................................................................................................................... 3 1

Introduction................................................................................................................................... 5 1.1

1.2 1.3 1.4

2

Design............................................................................................................................................ 6 2.1 2.2

3

3.2

Data Structure....................................................................................................................... 8 3.1.1 spi_transfer........................................................................................................... 8 3.1.2 spi_message ........................................................................................................ 9 3.1.3 spi_device ............................................................................................................ 9 3.1.4 mt6516_chip_conf .............................................................................................. 10 3.1.5 spi_board_info.................................................................................................... 11 Kernel Space Functions ..................................................................................................... 12 3.2.1 spi_setup ............................................................................................................ 12 3.2.2 spi_sync ............................................................................................................. 12 3.2.3 spi_message_init................................................................................................ 12 3.2.4 spi_message_add_tail........................................................................................ 13 3.2.5 spi_register_board_info...................................................................................... 13

Source code skeleton in Yusu .................................................................................................. 14 4.1 4.2

5

Architecture........................................................................................................................... 6 Procedure & Flow ................................................................................................................. 6

Interface......................................................................................................................................... 8 3.1

4

Software/Hardware Environment.......................................................................................... 5 1.1.1 Software Environment .......................................................................................... 5 1.1.2 Hardware Environment......................................................................................... 5 Functionality.......................................................................................................................... 5 Hardware background .......................................................................................................... 5 Hardware Component used in this driver ............................................................................. 5

SPI Controller driver ........................................................................................................... 14 SPI device driver ................................................................................................................ 14

Build............................................................................................................................................. 16

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5.1 5.2

Source Code Structure & File Description.......................................................................... 16 Build Option ........................................................................................................................ 16

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Lists of Tables and Figures

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Introduction

1.1

Software/Hardware Environment

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1

1.1.1

Software Environment

Driver discussed in this document is designed based on Linux Kernel 2.6.32 and Android 2.2.

1.1.2

Hardware Environment

Driver discussed in this document can run on the devices with MT6516.

1.2

Functionality

The driver is used to transfer data between master and slave. The main functionality is (1) Connect the SPI device by SPI bus provided by Linux kernel. (2) Provide parameters setting for SPI device.

1.3

Hardware background

N/A.

1.4

Hardware Component used in this driver

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It’s part of MT6516 chip.

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Design

2.1

Architecture

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2

SPI device Driver

SPI BUS ( Linux kernel core)

SPI device

SPI controller driver

Platform BUS

SPI controller

Note: 1) SPI controller is registered on platform bus. 2) SPI devices are registered on SPI bus.

2.2

Procedure & Flow

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In kernel space, SPI device driver is registered on SPI bus and calls the interfaces Linux kernel core provides. SPI controller driver is registered on platform bus and calls the interface of Linux kernel core.

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SPI bus

SPI Device

spi_setup

spi_sync

SPI Controller

mt6516_spi_setup

mt6516_spi_transfer

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The details of SPI bus interfaces will be introduced in the following chapters.

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Interface

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The chapter includes data structure and functions.

3.1

Data Structure

3.1.1

spi_transfer

This is one of the most important data structures of Linux Kernel core. struct spi_transfer { const void *tx_buf; void *rx_buf; unsigned len; dma_addr_t dma_addr_t

tx_dma; rx_dma;

unsigned cs_change:1; u8 bits_per_word; u16 delay_usecs; u32 speed_hz; struct list_head transfer_list;

};

The most important members of this structure are: tx_buf, rx_buf, len, tx_dma, rx_dma and transfer_list. tx_buf and rx_buf: transfer buffers for SPI data transferring. If data are written to hardware, tx_buf should be set as the address of the data; otherwise it should be set as NULL. If data are read from hardware, rx_buf should be set as the address of data; otherwise it should be set as NULL. tx_dma and rx_dma: DMA transfer buffers for DMA transferring. transfer_list: A transfer list which is composed of transfers. Note: For mt6516, rx_buf and tx_buf should be the address by using kmalloc.

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For example: u8 *tx_buffer=(u8 *)kzalloc(256, GFP_KERNEL); for (i=0; icontroller_data; config->pause=1; spi->controller_data=config;

3.1.4

mt6516_chip_conf

This structure is defined in mt6516_spi.h. It is used to set the parameters of the device chip. struct mt6516_chip_conf { u32 setuptime; u32 holdtime; u32 high_time; u32 low_time; u32 cs_idletime; enum spi_cpol cpol; enum spi_cpha cpha; enum spi_mlsb tx_mlsb; enum spi_mlsb rx_mlsb; enum spi_transfer_mode com_mod; enum spi_pause_mode pause; enum spi_finish_intr finish_intr; };

The parameters can be set as the private data of the device. And the controller can get by using this private data.

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For example: struct spi_device *spi; struct mt6516_chip_conf *config; config = (struct mt6516_chip_conf *)spi->controller_data; config->pause=1; spi->controller_data=config; spi_setup(spi);

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spi_board_info

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3.1.5

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This structure is to define a chip for the devices. This information is very important, because the SPI controller will add the devices to SPI bus according to the board info. struct spi_board_info { char modalias[SPI_NAME_SIZE]; const void *platform_data; void *controller_data; int irq;

/* slower signaling on noisy or low voltage boards */ u32 max_speed_hz; u16 u16

bus_num; chip_select;

u8

mode;

};

modalias: To identify the device. It should be same as the name of the device. Otherwise, this device can’t be identified. bus_num: the bus number of this board will be connected to. chip_select: Chip select number when multi devices exist. For mt6516: This structure is defined in the mt6516_devs.c.

static struct spi_board_info spi_board_devs[] __initdata = { [0] = { .modalias = "spidev", .bus_num = 0, .chip_select = 0, .mode=SPI_MODE_3, }, };

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If another device is to be added, just add one member to spi_board_devs. But for mt6516, until now only one device is supported. modalias: the name of the device. It should be the same as the name of SPI device driver. So if the names are different, the device can’t be connected to SPI bus. bus_num: the bus number of the spi controller. For mt6516, this should be 0, because there is only one spi controller. chip_select: the chip select number of spi device. This also should be 0, because for mt6516, only one device is supported.

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Kernel Space Functions

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3.2

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3.2.1

spi_setup

Set SPI device parameters. Prototype

int spi_setup (struct spi_device *spi) Parameters

struct spi_device

spi

SPI device structure.

Return Value

controller_data; config->pause=1; spi->controller_data=config; spi_setup(spi);

3.2.2

spi_sync

Start SPI data transfers. Prototype

int spi_sync(struct spi_device *spi, struct spi_message *message) Parameters

Struct spi_device

spi

The SPI device

Struct spi_message

message

The message which will be transferred.

Return Value