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(I'm so sorry!) Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327328329330331332333334335336337338339340341342343344345346347348349350351352// SPDX-License-Identifier: GPL-2.0-or-later/* * ee1004 - driver for DDR4 SPD EEPROMs * * Copyright (C) 2017-2019 Jean Delvare * * Based on the at24 driver: * Copyright (C) 2005-2007 David Brownell * Copyright (C) 2008 Wolfram Sang, Pengutronix */
#include <linux/device.h>#include <linux/i2c.h>#include <linux/init.h>#include <linux/kernel.h>#include <linux/module.h>#include <linux/mutex.h>#include <linux/nvmem-provider.h>
/* * DDR4 memory modules use special EEPROMs following the Jedec EE1004 * specification. These are 512-byte EEPROMs using a single I2C address * in the 0x50-0x57 range for data. One of two 256-byte page is selected * by writing a command to I2C address 0x36 or 0x37 on the same I2C bus. * * Therefore we need to request these 2 additional addresses, and serialize * access to all such EEPROMs with a single mutex. * * We assume it is safe to read up to 32 bytes at once from these EEPROMs. * We use SMBus access even if I2C is available, these EEPROMs are small * enough, and reading from them infrequent enough, that we favor simplicity * over performance. */
#define EE1004_MAX_BUSSES 8#define EE1004_ADDR_SET_PAGE 0x36#define EE1004_NUM_PAGES 2#define EE1004_PAGE_SIZE 256#define EE1004_PAGE_SHIFT 8#define EE1004_EEPROM_SIZE (EE1004_PAGE_SIZE * EE1004_NUM_PAGES)
/* * Mutex protects ee1004_set_page and ee1004_dev_count, and must be held * from page selection to end of read. */static DEFINE_MUTEX(ee1004_bus_lock);
static struct ee1004_bus_data { struct i2c_adapter *adap; struct i2c_client *set_page[EE1004_NUM_PAGES]; unsigned int dev_count; int current_page;} ee1004_bus_data[EE1004_MAX_BUSSES];
static const struct i2c_device_id ee1004_ids[] = { { "ee1004" }, { }};MODULE_DEVICE_TABLE(i2c, ee1004_ids);
/*-------------------------------------------------------------------------*/
static struct ee1004_bus_data *ee1004_get_bus_data(struct i2c_adapter *adap){ int i;
for (i = 0; i < EE1004_MAX_BUSSES; i++) if (ee1004_bus_data[i].adap == adap) return ee1004_bus_data + i;
/* If not existent yet, create new entry */ for (i = 0; i < EE1004_MAX_BUSSES; i++) if (!ee1004_bus_data[i].adap) { ee1004_bus_data[i].adap = adap; return ee1004_bus_data + i; }
return NULL;}
static int ee1004_get_current_page(struct ee1004_bus_data *bd){ int err;
err = i2c_smbus_read_byte(bd->set_page[0]); if (err == -ENXIO) { /* Nack means page 1 is selected */ return 1; } if (err < 0) { /* Anything else is a real error, bail out */ return err; }
/* Ack means page 0 is selected, returned value meaningless */ return 0;}
static int ee1004_set_current_page(struct i2c_client *client, int page){ struct ee1004_bus_data *bd = i2c_get_clientdata(client); int ret;
if (page == bd->current_page) return 0;
/* Data is ignored */ ret = i2c_smbus_write_byte(bd->set_page[page], 0x00); /* * Don't give up just yet. Some memory modules will select the page * but not ack the command. Check which page is selected now. */ if (ret == -ENXIO && ee1004_get_current_page(bd) == page) ret = 0; if (ret < 0) { dev_err(&client->dev, "Failed to select page %d (%d)\n", page, ret); return ret; }
dev_dbg(&client->dev, "Selected page %d\n", page); bd->current_page = page;
return 0;}
static ssize_t ee1004_eeprom_read(struct i2c_client *client, char *buf, unsigned int offset, size_t count){ int status, page;
page = offset >> EE1004_PAGE_SHIFT; offset &= (1 << EE1004_PAGE_SHIFT) - 1;
status = ee1004_set_current_page(client, page); if (status) return status;
/* Can't cross page boundaries */ if (offset + count > EE1004_PAGE_SIZE) count = EE1004_PAGE_SIZE - offset;
if (count > I2C_SMBUS_BLOCK_MAX) count = I2C_SMBUS_BLOCK_MAX;
return i2c_smbus_read_i2c_block_data_or_emulated(client, offset, count, buf);}
static int ee1004_read(void *priv, unsigned int off, void *val, size_t count){ struct i2c_client *client = priv; char *buf = val; int ret;
if (unlikely(!count)) return count;
if (off + count > EE1004_EEPROM_SIZE) return -EINVAL;
/* * Read data from chip, protecting against concurrent access to * other EE1004 SPD EEPROMs on the same adapter. */ mutex_lock(&ee1004_bus_lock);
while (count) { ret = ee1004_eeprom_read(client, buf, off, count); if (ret < 0) { mutex_unlock(&ee1004_bus_lock); return ret; }
buf += ret; off += ret; count -= ret; }
mutex_unlock(&ee1004_bus_lock);
return 0;}
static void ee1004_probe_temp_sensor(struct i2c_client *client){ struct i2c_board_info info = { .type = "jc42" }; unsigned short addr = 0x18 | (client->addr & 7); unsigned short addr_list[] = { addr, I2C_CLIENT_END }; u8 data[2]; int ret;
/* byte 14, bit 7 is set if temp sensor is present */ ret = ee1004_eeprom_read(client, data, 14, 1); if (ret != 1) return;
if (!(data[0] & BIT(7))) { /* * If the SPD data suggests that there is no temperature * sensor, it may still be there for SPD revision 1.0. * See SPD Annex L, Revision 1 and 2, for details. * Check DIMM type and SPD revision; if it is a DDR4 * with SPD revision 1.0, check the thermal sensor address * and instantiate the jc42 driver if a chip is found at * that address. * It is not necessary to check if there is a chip at the * temperature sensor address since i2c_new_scanned_device() * will do that and return silently if no chip is found. */ ret = ee1004_eeprom_read(client, data, 1, 2); if (ret != 2 || data[0] != 0x10 || data[1] != 0x0c) return; } i2c_new_scanned_device(client->adapter, &info, addr_list, NULL);}
static void ee1004_cleanup(int idx, struct ee1004_bus_data *bd){ if (--bd->dev_count == 0) { while (--idx >= 0) i2c_unregister_device(bd->set_page[idx]); memset(bd, 0, sizeof(struct ee1004_bus_data)); }}
static void ee1004_cleanup_bus_data(void *data){ struct ee1004_bus_data *bd = data;
/* Remove page select clients if this is the last device */ mutex_lock(&ee1004_bus_lock); ee1004_cleanup(EE1004_NUM_PAGES, bd); mutex_unlock(&ee1004_bus_lock);}
static int ee1004_init_bus_data(struct i2c_client *client){ struct ee1004_bus_data *bd; int err, cnr = 0;
bd = ee1004_get_bus_data(client->adapter); if (!bd) return dev_err_probe(&client->dev, -ENOSPC, "Only %d busses supported", EE1004_MAX_BUSSES);
i2c_set_clientdata(client, bd);
if (++bd->dev_count == 1) { /* Use 2 dummy devices for page select command */ for (cnr = 0; cnr < EE1004_NUM_PAGES; cnr++) { struct i2c_client *cl;
cl = i2c_new_dummy_device(client->adapter, EE1004_ADDR_SET_PAGE + cnr); if (IS_ERR(cl)) { err = PTR_ERR(cl); goto err_out; }
bd->set_page[cnr] = cl; }
/* Remember current page to avoid unneeded page select */ err = ee1004_get_current_page(bd); if (err < 0) goto err_out;
dev_dbg(&client->dev, "Currently selected page: %d\n", err); bd->current_page = err; }
return 0;
err_out: ee1004_cleanup(cnr, bd);
return err;}
static int ee1004_probe(struct i2c_client *client){ struct nvmem_config config = { .dev = &client->dev, .name = dev_name(&client->dev), .id = NVMEM_DEVID_NONE, .owner = THIS_MODULE, .type = NVMEM_TYPE_EEPROM, .read_only = true, .root_only = false, .reg_read = ee1004_read, .size = EE1004_EEPROM_SIZE, .word_size = 1, .stride = 1, .priv = client, .compat = true, .base_dev = &client->dev, }; struct nvmem_device *ndev; int err;
/* Make sure we can operate on this adapter */ if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE | I2C_FUNC_SMBUS_READ_I2C_BLOCK) && !i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE | I2C_FUNC_SMBUS_READ_BYTE_DATA)) return -EPFNOSUPPORT;
err = i2c_smbus_read_byte(client); if (err < 0) return -ENODEV;
mutex_lock(&ee1004_bus_lock);
err = ee1004_init_bus_data(client); if (err < 0) { mutex_unlock(&ee1004_bus_lock); return err; }
ee1004_probe_temp_sensor(client);
mutex_unlock(&ee1004_bus_lock);
err = devm_add_action_or_reset(&client->dev, ee1004_cleanup_bus_data, i2c_get_clientdata(client)); if (err < 0) return err;
ndev = devm_nvmem_register(&client->dev, &config); if (IS_ERR(ndev)) return PTR_ERR(ndev);
dev_info(&client->dev, "%u byte EE1004-compliant SPD EEPROM, read-only\n", EE1004_EEPROM_SIZE);
return 0;}
/*-------------------------------------------------------------------------*/
static struct i2c_driver ee1004_driver = { .driver = { .name = "ee1004", }, .probe = ee1004_probe, .id_table = ee1004_ids,};module_i2c_driver(ee1004_driver);
MODULE_DESCRIPTION("Driver for EE1004-compliant DDR4 SPD EEPROMs");MODULE_AUTHOR("Jean Delvare");MODULE_LICENSE("GPL");