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Annotation of qemu/roms/ipxe/src/drivers/nvs/spi.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (C) 2006 Michael Brown <[email protected]>.
        !             3:  *
        !             4:  * This program is free software; you can redistribute it and/or
        !             5:  * modify it under the terms of the GNU General Public License as
        !             6:  * published by the Free Software Foundation; either version 2 of the
        !             7:  * License, or any later version.
        !             8:  *
        !             9:  * This program is distributed in the hope that it will be useful, but
        !            10:  * WITHOUT ANY WARRANTY; without even the implied warranty of
        !            11:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
        !            12:  * General Public License for more details.
        !            13:  *
        !            14:  * You should have received a copy of the GNU General Public License
        !            15:  * along with this program; if not, write to the Free Software
        !            16:  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
        !            17:  */
        !            18: 
        !            19: FILE_LICENCE ( GPL2_OR_LATER );
        !            20: 
        !            21: #include <stddef.h>
        !            22: #include <errno.h>
        !            23: #include <unistd.h>
        !            24: #include <ipxe/spi.h>
        !            25: 
        !            26: /** @file
        !            27:  *
        !            28:  * SPI devices
        !            29:  *
        !            30:  */
        !            31: 
        !            32: /**
        !            33:  * Munge SPI device address into command
        !            34:  *
        !            35:  * @v command          SPI command
        !            36:  * @v address          Address
        !            37:  * @v munge_address    Device requires address munging
        !            38:  * @ret command                Actual SPI command to use
        !            39:  *
        !            40:  * Some devices with 9-bit addresses (e.g. AT25040A EEPROM) use bit 3
        !            41:  * of the command byte as address bit A8, rather than having a
        !            42:  * two-byte address.  This function takes care of generating the
        !            43:  * appropriate command.
        !            44:  */
        !            45: static inline unsigned int spi_command ( unsigned int command,
        !            46:                                         unsigned int address,
        !            47:                                         int munge_address ) {
        !            48:        return ( command | ( ( ( address >> 8 ) & munge_address ) << 3 ) );
        !            49: }
        !            50: 
        !            51: /**
        !            52:  * Wait for SPI device to complete operation
        !            53:  *
        !            54:  * @v device           SPI device
        !            55:  * @ret rc             Return status code
        !            56:  */
        !            57: static int spi_wait ( struct spi_device *device ) {
        !            58:        struct spi_bus *bus = device->bus;
        !            59:        uint8_t status;
        !            60:        int i;
        !            61:        int rc;
        !            62: 
        !            63:        for ( i = 0 ; i < 50 ; i++ ) {
        !            64:                udelay ( 20 );
        !            65:                if ( ( rc = bus->rw ( bus, device, SPI_RDSR, -1, NULL,
        !            66:                                      &status, sizeof ( status ) ) ) != 0 )
        !            67:                        return rc;
        !            68:                if ( ! ( status & SPI_STATUS_NRDY ) )
        !            69:                        return 0;
        !            70:        }
        !            71:        DBG ( "SPI %p timed out\n", device );
        !            72:        return -ETIMEDOUT;
        !            73: }
        !            74: 
        !            75: /**
        !            76:  * Read data from SPI device
        !            77:  *
        !            78:  * @v nvs              NVS device
        !            79:  * @v address          Address from which to read
        !            80:  * @v data             Data buffer
        !            81:  * @v len              Length of data buffer
        !            82:  * @ret rc             Return status code
        !            83:  */
        !            84: int spi_read ( struct nvs_device *nvs, unsigned int address,
        !            85:               void *data, size_t len ) {
        !            86:        struct spi_device *device = nvs_to_spi ( nvs );
        !            87:        struct spi_bus *bus = device->bus;
        !            88:        unsigned int command = spi_command ( SPI_READ, address,
        !            89:                                             device->munge_address );
        !            90:        int rc;
        !            91: 
        !            92:        DBG ( "SPI %p reading %zd bytes from %#04x\n", device, len, address );
        !            93:        if ( ( rc = bus->rw ( bus, device, command, address,
        !            94:                              NULL, data, len ) ) != 0 ) {
        !            95:                DBG ( "SPI %p failed to read data from device\n", device );
        !            96:                return rc;
        !            97:        }
        !            98: 
        !            99:        return 0;
        !           100: }
        !           101: 
        !           102: /**
        !           103:  * Write data to SPI device
        !           104:  *
        !           105:  * @v nvs              NVS device
        !           106:  * @v address          Address from which to read
        !           107:  * @v data             Data buffer
        !           108:  * @v len              Length of data buffer
        !           109:  * @ret rc             Return status code
        !           110:  */
        !           111: int spi_write ( struct nvs_device *nvs, unsigned int address,
        !           112:                const void *data, size_t len ) {
        !           113:        struct spi_device *device = nvs_to_spi ( nvs );
        !           114:        struct spi_bus *bus = device->bus;
        !           115:        unsigned int command = spi_command ( SPI_WRITE, address,
        !           116:                                             device->munge_address );
        !           117:        int rc;
        !           118: 
        !           119:        DBG ( "SPI %p writing %zd bytes to %#04x\n", device, len, address );
        !           120: 
        !           121:        if ( ( rc = bus->rw ( bus, device, SPI_WREN, -1,
        !           122:                              NULL, NULL, 0 ) ) != 0 ) {
        !           123:                DBG ( "SPI %p failed to write-enable device\n", device );
        !           124:                return rc;
        !           125:        }
        !           126: 
        !           127:        if ( ( rc = bus->rw ( bus, device, command, address,
        !           128:                              data, NULL, len ) ) != 0 ) {
        !           129:                DBG ( "SPI %p failed to write data to device\n", device );
        !           130:                return rc;
        !           131:        }
        !           132:        
        !           133:        if ( ( rc = spi_wait ( device ) ) != 0 ) {
        !           134:                DBG ( "SPI %p failed to complete write operation\n", device );
        !           135:                return rc;
        !           136:        }
        !           137: 
        !           138:        return 0;
        !           139: }
        !           140: 

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