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Add an I2C transport driver for the Versal SysMon block. The SysMon provides an I2C slave interface that allows an external master to read voltage and temperature measurements through the same register map used by the MMIO path. The I2C command frame is an 8-byte structure containing a 4-byte data payload, a 2-byte register offset, and a 1-byte instruction field. Read operations send the frame with a read instruction, then receive a 4-byte response containing the register value. Events are not supported on the I2C path because there is no interrupt line and the I2C regmap backend cannot be called from atomic context. Co-developed-by: Conall O'Griofa <conall.ogriofa@amd.com> Signed-off-by: Conall O'Griofa <conall.ogriofa@amd.com> Signed-off-by: Salih Erim <salih.erim@amd.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com> Signed-off-by: Jonathan Cameron <jic23@kernel.org>
135 lines
3.3 KiB
C
135 lines
3.3 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* AMD Versal SysMon I2C driver
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*
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* Copyright (C) 2023 - 2026, Advanced Micro Devices, Inc.
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*/
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#include <linux/bits.h>
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#include <linux/err.h>
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#include <linux/i2c.h>
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#include <linux/mod_devicetable.h>
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#include <linux/module.h>
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#include <linux/regmap.h>
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#include <linux/types.h>
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#include <linux/unaligned.h>
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#include "versal-sysmon.h"
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#define SYSMON_I2C_INSTR_READ BIT(2)
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#define SYSMON_I2C_INSTR_WRITE BIT(3)
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/*
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* I2C command frame layout (8 bytes):
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* [0..3] data payload (little-endian u32)
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* [4..5] register offset >> 2 (little-endian u16)
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* [6] instruction (read/write)
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* [7] reserved
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*/
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#define SYSMON_I2C_DATA_OFS 0
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#define SYSMON_I2C_REG_OFS 4
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#define SYSMON_I2C_INSTR_OFS 6
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static int sysmon_i2c_reg_read(void *context, unsigned int reg,
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unsigned int *val)
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{
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struct i2c_client *client = context;
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u8 write_buf[8] = { };
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u8 read_buf[4];
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int ret;
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put_unaligned_le16(reg >> 2, &write_buf[SYSMON_I2C_REG_OFS]);
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write_buf[SYSMON_I2C_INSTR_OFS] = SYSMON_I2C_INSTR_READ;
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ret = i2c_master_send(client, write_buf, sizeof(write_buf));
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if (ret < 0)
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return ret;
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if (ret != sizeof(write_buf))
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return -EIO;
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ret = i2c_master_recv(client, read_buf, sizeof(read_buf));
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if (ret < 0)
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return ret;
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if (ret != sizeof(read_buf))
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return -EIO;
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*val = get_unaligned_le32(read_buf);
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return 0;
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}
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static int sysmon_i2c_reg_write(void *context, unsigned int reg,
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unsigned int val)
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{
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struct i2c_client *client = context;
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u8 write_buf[8] = { };
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int ret;
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put_unaligned_le32(val, &write_buf[SYSMON_I2C_DATA_OFS]);
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put_unaligned_le16(reg >> 2, &write_buf[SYSMON_I2C_REG_OFS]);
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write_buf[SYSMON_I2C_INSTR_OFS] = SYSMON_I2C_INSTR_WRITE;
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ret = i2c_master_send(client, write_buf, sizeof(write_buf));
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if (ret < 0)
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return ret;
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if (ret != sizeof(write_buf))
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return -EIO;
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return 0;
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}
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/*
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* Almost all registers are volatile (live ADC readings, interrupt
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* status). The rest are not accessed often enough to benefit from
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* caching.
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*/
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static const struct regmap_config sysmon_i2c_regmap_config = {
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.reg_bits = 32,
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.val_bits = 32,
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.reg_stride = SYSMON_REG_STRIDE,
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.max_register = SYSMON_MAX_REG,
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.reg_read = sysmon_i2c_reg_read,
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.reg_write = sysmon_i2c_reg_write,
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};
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static int sysmon_i2c_probe(struct i2c_client *client)
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{
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struct device *dev = &client->dev;
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struct regmap *regmap;
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regmap = devm_regmap_init(dev, NULL, client, &sysmon_i2c_regmap_config);
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if (IS_ERR(regmap))
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return PTR_ERR(regmap);
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/* I2C has no IRQ connection; events are not supported */
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return devm_versal_sysmon_core_probe(dev, regmap);
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}
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static const struct of_device_id sysmon_i2c_of_match_table[] = {
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{ .compatible = "xlnx,versal-sysmon" },
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{ }
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};
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MODULE_DEVICE_TABLE(of, sysmon_i2c_of_match_table);
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static const struct i2c_device_id sysmon_i2c_id_table[] = {
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{ .name = "versal-sysmon" },
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{ }
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};
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MODULE_DEVICE_TABLE(i2c, sysmon_i2c_id_table);
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static struct i2c_driver sysmon_i2c_driver = {
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.probe = sysmon_i2c_probe,
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.driver = {
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.name = "versal-sysmon-i2c",
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.of_match_table = sysmon_i2c_of_match_table,
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},
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.id_table = sysmon_i2c_id_table,
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};
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module_i2c_driver(sysmon_i2c_driver);
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MODULE_LICENSE("GPL");
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MODULE_DESCRIPTION("AMD Versal SysMon I2C Driver");
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MODULE_IMPORT_NS("VERSAL_SYSMON");
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MODULE_AUTHOR("Conall O'Griofa <conall.ogriofa@amd.com>");
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MODULE_AUTHOR("Salih Erim <salih.erim@amd.com>");
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