1.\" Copyright (c) 2018 Emmanuel Vadot <manu@freebsd.org> 2.\" 3.\" Redistribution and use in source and binary forms, with or without 4.\" modification, are permitted provided that the following conditions 5.\" are met: 6.\" 1. Redistributions of source code must retain the above copyright 7.\" notice, this list of conditions and the following disclaimer. 8.\" 2. Redistributions in binary form must reproduce the above copyright 9.\" notice, this list of conditions and the following disclaimer in the 10.\" documentation and/or other materials provided with the distribution. 11.\" 12.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR 13.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 14.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 15.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT, 16.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 17.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 18.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 19.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 20.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 21.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 22.\" 23.Dd July 24, 2018 24.Dt nvmem 9 25.Os 26.Sh NAME 27.Nm nvmem , 28.Nm nvmem_get_cell_len , 29.Nm nvmem_read_cell_by_name , 30.Nm nvmem_read_cell_by_idx , 31.Nm nvmem_write_cell_by_name , 32.Nm nvmem_write_cell_by_idx 33.Sh SYNOPSIS 34.Cd "options FDT" 35.Cd "device nvmem" 36.In sys/extres/nvmem/nvmem.h 37.Ft int 38.Fn nvmem_get_cell_len "phandle_t node" "const char *name" 39.Ft int 40.Fn nvmem_read_cell_by_name "phandle_t node" "const char *name" "void *cell" "size_t buflen" 41.Ft int 42.Fn nvmem_read_cell_by_idx "phandle_t node" "int idx" "void *cell" "size_t buflen" 43.Ft int 44.Fn nvmem_write_cell_by_name "phandle_t node" "const char *name" "void *cell" "size_t buflen" 45.Ft int 46.Fn nvmem_write_cell_by_idx "phandle_t node" "int idx" "void *cell" "size_t buflen" 47.Sh DESCRIPTION 48On some embedded boards, the manufacturer stored some data on a NVMEM 49(Non-Volatile Memory), this is generally stored in some eeprom or fuses. 50.Pp 51The 52.Nm 53API consist of helpers functions for consumer and device methods for 54providers. 55.Sh FUNCTIONS 56.Bl -tag -width indent 57.It Fn nvmem_get_cell_len "phandle_t node" "const char *name" 58Get the size of the cell base on the reg property on the node. 59Return the size or ENOENT if the cell name wasn't found 60.It Fn nvmem_read_cell_by_name "phandle_t node" "const char *name" "void *cell" "size_t buflen" 61Get the cell content based on the name. 62Return 0 on sucess or ENOENT if the cell doesn't exists, ENXIO if no provider device was found, 63EINVAL if the size isn't correct. 64.It Fn nvmem_read_cell_by_idx "phandle_t node" "int idx" "void *cell" "size_t buflen" 65Get the cell content based on the id. 66Return 0 on sucess or ENOENT if the cell doesn't exists, ENXIO if no provider device was found, 67EINVAL if the size isn't correct. 68.It Fn nvmem_write_cell_by_name "phandle_t node" "const char *name" "void *cell" "size_t buflen" 69Write the cell content based on the name. 70Return 0 on sucess or ENOENT if the cell doesn't exists, ENXIO if no provider device was found, 71EINVAL if the size isn't correct. 72.It Fn nvmem_write_cell_by_idx "phandle_t node" "int idx" "void *cell" "size_t buflen" 73Write the cell content based on the id. 74Return 0 on sucess or ENOENT if the cell doesn't exists, ENXIO if no provider device was found, 75EINVAL if the size isn't correct. 76.El 77.Sh DEVICE METHODS 78.Bl -tag -width indent 79.It Fn nvmem_read "device_t dev" "uint32_t offset" "uint32_t size" "uint8_t *buffer" 80Provider device method to read a cell content. 81.It Fn nvmem_write "device_t dev" "uint32_t offset" "uint32_t size" "uint8_t *buffer" 82Provider device method to write a cell content. 83.El 84.Sh EXAMPLES 85Consider this DTS 86.Bd -literal 87/* Provider */ 88eeprom: eeprom@20000 { 89 board_id: id@0 { 90 reg = <0x0 0x4>; 91 }; 92}; 93/* Consumer */ 94device@30000 { 95 ... 96 97 nvmem-cells = <&board_id> 98 nvmem-cell-names = "boardid"; 99}; 100.Ed 101.Pp 102The device driver for eeprom@20000 needs to expose itself as a provider 103.Bd -literal 104#include "nvmem_if.h" 105 106int 107foo_nvmem_read(device_t dev, uint32_t offset, uint32_t size, uint8_t *buffer) 108{ 109 /* Read the data */ 110} 111 112int 113foo_attach(device_t dev) 114{ 115 phandle_t node; 116 117 node = ofw_bus_get_node(dev); 118 ... 119 /* Registering the device so the consumers can find us */ 120 OF_device_register_xref(OF_xref_from_node(node), dev); 121 122 ... 123} 124 125static device_method_t foo_methods[] = { 126 ... 127 128 /* nvmem interface */ 129 DEVMETHOD(nvmem_read, foo_nvmem_read), 130 131 /* Terminate method list */ 132 DEVMETHOD_END 133}; 134.Ed 135.Pp 136The consumer device driver for device@30000 can now read the nvmem data 137.Bd -literal 138int 139bar_attach(device_t dev) 140{ 141 phandle_t node; 142 uint32_t boardid; 143 144 ... 145 node = ofw_bus_get_node(dev); 146 nvmem_read_cell_by_name(node, "boardid", (void *)&boardid, sizeof(boardid)); 147 ... 148} 149.Ed 150.Sh HISTORY 151The nvmem related function first appear in 152.Fx 12.0 . 153The nvmem interface and manual page was written by 154.An Emmanuel Vadot Aq Mt manu@FreeBSD.org . 155