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diff --git a/ecos/packages/devs/eth/phy/current/doc/eth_phy.sgml b/ecos/packages/devs/eth/phy/current/doc/eth_phy.sgml new file mode 100644 index 0000000..35ccdda --- /dev/null +++ b/ecos/packages/devs/eth/phy/current/doc/eth_phy.sgml @@ -0,0 +1,172 @@ +<!-- {{{ Banner --> + +<!-- =============================================================== --> +<!-- --> +<!-- eth_phy.sgml --> +<!-- --> +<!-- eCos ethernet PHY device driver documentation --> +<!-- --> +<!-- =============================================================== --> +<!-- ####ECOSDOCCOPYRIGHTBEGIN#### --> +<!-- =============================================================== --> +<!-- Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2010 Free Software Foundation, Inc. --> +<!-- This material may be distributed only subject to the terms --> +<!-- and conditions set forth in the Open Publication License, v1.0 --> +<!-- or later (the latest version is presently available at --> +<!-- http://www.opencontent.org/openpub/) --> +<!-- Distribution of the work or derivative of the work in any --> +<!-- standard (paper) book form is prohibited unless prior --> +<!-- permission obtained from the copyright holder --> +<!-- =============================================================== --> +<!-- ####ECOSDOCCOPYRIGHTEND#### --> +<!-- =============================================================== --> +<!-- #####DESCRIPTIONBEGIN#### --> +<!-- --> +<!-- ####DESCRIPTIONEND#### --> +<!-- =============================================================== --> + +<!-- }}} --> + +<part id="io-eth-phy-generic"> +<title>Ethernet PHY Device Support</title> +<chapter id="io-eth-phy-generic1"> +<title>Ethernet PHY Device Support</title> +<sect1 id="io-eth-phy-api"> +<title>Ethernet PHY Device API</title> +<para> +Modern ethernet subsystems are often separated into two pieces, the +media access controller (sometimes known as a MAC) and the physical +device or line interface (often referred to as a PHY). In this case, +the MAC handles generating and parsing physical frames and the PHY +handles how this data is actually moved to/from the wire. The MAC +and PHY communicate via a special protocol, known as MII. This MII +protocol can handle control over the PHY which allows for selection +of such transmission criteria as line speed, duplex mode, etc. +</para> +<para> +In most cases, ethernet drivers only need to bother with the PHY during +system initialization. Since the details of the PHY are separate from +the MAC, there are different drivers for each. The drivers for the PHY +are described by a set of exported functions which are commonly used by +the MAC. The primary use of these functions currently is to initialize +the PHY and determine the status of the line connection. +</para> +<para> +The connection between the MAC and the PHY differs from MAC to MAC, so +the actual routines to manipulate this data channel are a property of +the MAC instance. Furthermore, there are many PHY devices each with their +own internal operations. A complete MAC/PHY driver setup will be comprised +of the MAC MII access functions and the PHY internal driver. +</para> +<para> +A driver instance is contained within a +<type>eth_phy_access_t</type>: +<programlisting> + +#define PHY_BIT_LEVEL_ACCESS_TYPE 0 +#define PHY_REG_LEVEL_ACCESS_TYPE 1 + +typedef struct { + int ops_type; // 0 => bit level, 1 => register level + bool init_done; + void (*init)(void); + void (*reset)(void); + union { + struct { + void (*set_data)(int); + int (*get_data)(void); + void (*set_clock)(int); + void (*set_dir)(int); + } bit_level_ops; + struct { + void (*put_reg)(int reg, int unit, unsigned short data); + bool (*get_reg)(int reg, int unit, unsigned short *data); + } reg_level_ops; + } ops; + int phy_addr; + struct _eth_phy_dev_entry *dev; // Chip access functions +} eth_phy_access_t; + +struct _eth_phy_dev_entry { + char *name; + unsigned long id; + bool (*stat)(eth_phy_access_t *f, int *stat); +}; + +</programlisting> +The <varname>dev</varname> element points to the PHY specific support +functions. +Currently, the only function which must be defined is <function>stat()</function>. +</para> +<para> +The MAC-MII-PHY interface is a narrow connection, with commands and status +moving between the MAC and PHY using a bit-serial protocol. +Some MAC devices contain the intelligence to run this protocol, exposing +a mechanism to access PHY registers one at a time. Other MAC devices may only +provide access to the MII data lines (or even still, this may be considered +completely separate from the MAC). In these cases, the PHY support layer +must handle the serial protocol. +The choice between the access methods is in the +<varname>ops_type</varname> field. +If it has the value +<varname>PHY_BIT_LEVEL_ACCESS_TYPE</varname>, then the PHY device layer will +run the protocol, using the access functions +<function>set_data()</function>, +<function>get_data()</function>, +<function>set_clock()</function>, +<function>set_dir()</function> are used to control the MII signals and run +the protocol. +If <varname>ops_type</varname> has the value +<varname>PHY_REG_LEVEL_ACCESS_TYPE</varname>, +then the routines +<function>put_reg()</function>, and +<function>get_reg()</function> +are used to access the PHY registers. +</para> +<para> +Two additional functions may be defined. +These are +<function>init()</function>, and +<function>reset()</function>. +The purpose of these functions is for gross-level management of the +MII interface. +The +<function>init()</function> +function will be called once, at system initialization time. +It should do whatever operations are necessary to prepare the +MII channel. +In the case of +<varname>PHY_BIT_LEVEL_ACCESS_TYPE</varname> devices, +<function>init()</function> +should prepare the signals for use, i.e. set up the appropriate +parallel port registers, etc. +The +<function>reset()</function> +function may be called by a driver to cause the PHY device to +be reset to a known state. +Not all drivers will require this and this function may not even +be possible, so it's use and behavior is somewhat target specific. +</para> +<para> +Currently, the only function required of device specific drivers is +<function>stat()</function>. +This routine should query appropriate registers in the PHY and return +a status bitmap indicating the state of the physical connection. +In the case where the PHY can auto-negotiate a line speed and condition, +this information may be useful to the MAC to indicate what speed it should +provide data, etc. +The status bitmask contains these bits: +<programlisting> +#define ETH_PHY_STAT_LINK 0x0001 // Link up/down +#define ETH_PHY_STAT_100MB 0x0002 // Connection is 100Mb/10Mb +#define ETH_PHY_STAT_FDX 0x0004 // Connection is full/half duplex +#define ETH_PHY_STAT_1000MB 0x0008 // Connection is 1Gb +</programlisting> +Note: the usage here is that if the bit is set, then the condition +exists. For example, if the +<varname>ETH_PHY_STAT_LINK</varname> +is set, then a physical link has been established. +</para> +</sect1> +</chapter> +</part> |