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// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
//
// AMD SPI controller driver
//
// Copyright (c) 2020, Advanced Micro Devices, Inc.
//
// Author: Sanjay R Mehta <sanju.mehta@amd.com>
#include <linux/acpi.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/delay.h>
#include <linux/spi/spi.h>
#define AMD_SPI_CTRL0_REG 0x00
#define AMD_SPI_EXEC_CMD BIT(16)
#define AMD_SPI_FIFO_CLEAR BIT(20)
#define AMD_SPI_BUSY BIT(31)
#define AMD_SPI_OPCODE_MASK 0xFF
#define AMD_SPI_ALT_CS_REG 0x1D
#define AMD_SPI_ALT_CS_MASK 0x3
#define AMD_SPI_FIFO_BASE 0x80
#define AMD_SPI_TX_COUNT_REG 0x48
#define AMD_SPI_RX_COUNT_REG 0x4B
#define AMD_SPI_STATUS_REG 0x4C
#define AMD_SPI_MEM_SIZE 200
/* M_CMD OP codes for SPI */
#define AMD_SPI_XFER_TX 1
#define AMD_SPI_XFER_RX 2
struct amd_spi {
void __iomem *io_remap_addr;
unsigned long io_base_addr;
u32 rom_addr;
u8 chip_select;
};
static inline u8 amd_spi_readreg8(struct spi_master *master, int idx)
{
struct amd_spi *amd_spi = spi_master_get_devdata(master);
return ioread8((u8 __iomem *)amd_spi->io_remap_addr + idx);
}
static inline void amd_spi_writereg8(struct spi_master *master, int idx,
u8 val)
{
struct amd_spi *amd_spi = spi_master_get_devdata(master);
iowrite8(val, ((u8 __iomem *)amd_spi->io_remap_addr + idx));
}
static inline void amd_spi_setclear_reg8(struct spi_master *master, int idx,
u8 set, u8 clear)
{
u8 tmp = amd_spi_readreg8(master, idx);
tmp = (tmp & ~clear) | set;
amd_spi_writereg8(master, idx, tmp);
}
static inline u32 amd_spi_readreg32(struct spi_master *master, int idx)
{
struct amd_spi *amd_spi = spi_master_get_devdata(master);
return ioread32((u8 __iomem *)amd_spi->io_remap_addr + idx);
}
static inline void amd_spi_writereg32(struct spi_master *master, int idx,
u32 val)
{
struct amd_spi *amd_spi = spi_master_get_devdata(master);
iowrite32(val, ((u8 __iomem *)amd_spi->io_remap_addr + idx));
}
static inline void amd_spi_setclear_reg32(struct spi_master *master, int idx,
u32 set, u32 clear)
{
u32 tmp = amd_spi_readreg32(master, idx);
tmp = (tmp & ~clear) | set;
amd_spi_writereg32(master, idx, tmp);
}
static void amd_spi_select_chip(struct spi_master *master)
{
struct amd_spi *amd_spi = spi_master_get_devdata(master);
u8 chip_select = amd_spi->chip_select;
amd_spi_setclear_reg8(master, AMD_SPI_ALT_CS_REG, chip_select,
AMD_SPI_ALT_CS_MASK);
}
static void amd_spi_clear_fifo_ptr(struct spi_master *master)
{
amd_spi_setclear_reg32(master, AMD_SPI_CTRL0_REG, AMD_SPI_FIFO_CLEAR,
AMD_SPI_FIFO_CLEAR);
}
static void amd_spi_set_opcode(struct spi_master *master, u8 cmd_opcode)
{
amd_spi_setclear_reg32(master, AMD_SPI_CTRL0_REG, cmd_opcode,
AMD_SPI_OPCODE_MASK);
}
static inline void amd_spi_set_rx_count(struct spi_master *master,
u8 rx_count)
{
amd_spi_setclear_reg8(master, AMD_SPI_RX_COUNT_REG, rx_count, 0xff);
}
static inline void amd_spi_set_tx_count(struct spi_master *master,
u8 tx_count)
{
amd_spi_setclear_reg8(master, AMD_SPI_TX_COUNT_REG, tx_count, 0xff);
}
static inline int amd_spi_busy_wait(struct amd_spi *amd_spi)
{
bool spi_busy;
int timeout = 100000;
/* poll for SPI bus to become idle */
spi_busy = (ioread32((u8 __iomem *)amd_spi->io_remap_addr +
AMD_SPI_CTRL0_REG) & AMD_SPI_BUSY) == AMD_SPI_BUSY;
while (spi_busy) {
usleep_range(10, 20);
if (timeout-- < 0)
return -ETIMEDOUT;
spi_busy = (ioread32((u8 __iomem *)amd_spi->io_remap_addr +
AMD_SPI_CTRL0_REG) & AMD_SPI_BUSY) == AMD_SPI_BUSY;
}
return 0;
}
static void amd_spi_execute_opcode(struct spi_master *master)
{
struct amd_spi *amd_spi = spi_master_get_devdata(master);
/* Set ExecuteOpCode bit in the CTRL0 register */
amd_spi_setclear_reg32(master, AMD_SPI_CTRL0_REG, AMD_SPI_EXEC_CMD,
AMD_SPI_EXEC_CMD);
amd_spi_busy_wait(amd_spi);
}
static int amd_spi_master_setup(struct spi_device *spi)
{
struct spi_master *master = spi->master;
amd_spi_clear_fifo_ptr(master);
return 0;
}
static inline int amd_spi_fifo_xfer(struct amd_spi *amd_spi,
struct spi_master *master,
struct spi_message *message)
{
struct spi_transfer *xfer = NULL;
u8 cmd_opcode;
u8 *buf = NULL;
u32 m_cmd = 0;
u32 i = 0;
u32 tx_len = 0, rx_len = 0;
list_for_each_entry(xfer, &message->transfers,
transfer_list) {
if (xfer->rx_buf)
m_cmd = AMD_SPI_XFER_RX;
if (xfer->tx_buf)
m_cmd = AMD_SPI_XFER_TX;
if (m_cmd & AMD_SPI_XFER_TX) {
buf = (u8 *)xfer->tx_buf;
tx_len = xfer->len - 1;
cmd_opcode = *(u8 *)xfer->tx_buf;
buf++;
amd_spi_set_opcode(master, cmd_opcode);
/* Write data into the FIFO. */
for (i = 0; i < tx_len; i++) {
iowrite8(buf[i],
((u8 __iomem *)amd_spi->io_remap_addr +
AMD_SPI_FIFO_BASE + i));
}
amd_spi_set_tx_count(master, tx_len);
amd_spi_clear_fifo_ptr(master);
/* Execute command */
amd_spi_execute_opcode(master);
}
if (m_cmd & AMD_SPI_XFER_RX) {
/*
* Store no. of bytes to be received from
* FIFO
*/
rx_len = xfer->len;
buf = (u8 *)xfer->rx_buf;
amd_spi_set_rx_count(master, rx_len);
amd_spi_clear_fifo_ptr(master);
/* Execute command */
amd_spi_execute_opcode(master);
/* Read data from FIFO to receive buffer */
for (i = 0; i < rx_len; i++)
buf[i] = amd_spi_readreg8(master,
AMD_SPI_FIFO_BASE +
tx_len + i);
}
}
/* Update statistics */
message->actual_length = tx_len + rx_len + 1;
/* complete the transaction */
message->status = 0;
spi_finalize_current_message(master);
return 0;
}
static int amd_spi_master_transfer(struct spi_master *master,
struct spi_message *msg)
{
struct amd_spi *amd_spi = spi_master_get_devdata(master);
struct spi_device *spi = msg->spi;
amd_spi->chip_select = spi->chip_select;
amd_spi_select_chip(master);
/*
* Extract spi_transfers from the spi message and
* program the controller.
*/
amd_spi_fifo_xfer(amd_spi, master, msg);
return 0;
}
static int amd_spi_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct spi_master *master;
struct amd_spi *amd_spi;
struct resource *res;
int err = 0;
/* Allocate storage for spi_master and driver private data */
master = spi_alloc_master(dev, sizeof(struct amd_spi));
if (!master) {
dev_err(dev, "Error allocating SPI master\n");
return -ENOMEM;
}
amd_spi = spi_master_get_devdata(master);
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
amd_spi->io_remap_addr = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(amd_spi->io_remap_addr)) {
err = PTR_ERR(amd_spi->io_remap_addr);
dev_err(dev, "error %d ioremap of SPI registers failed\n", err);
goto err_free_master;
}
dev_dbg(dev, "io_remap_address: %p\n", amd_spi->io_remap_addr);
/* Initialize the spi_master fields */
master->bus_num = 0;
master->num_chipselect = 4;
master->mode_bits = 0;
master->flags = SPI_MASTER_HALF_DUPLEX;
master->setup = amd_spi_master_setup;
master->transfer_one_message = amd_spi_master_transfer;
/* Register the controller with SPI framework */
err = devm_spi_register_master(dev, master);
if (err) {
dev_err(dev, "error %d registering SPI controller\n", err);
goto err_free_master;
}
return 0;
err_free_master:
spi_master_put(master);
return err;
}
static const struct acpi_device_id spi_acpi_match[] = {
{ "AMDI0061", 0 },
{},
};
MODULE_DEVICE_TABLE(acpi, spi_acpi_match);
static struct platform_driver amd_spi_driver = {
.driver = {
.name = "amd_spi",
.acpi_match_table = ACPI_PTR(spi_acpi_match),
},
.probe = amd_spi_probe,
};
module_platform_driver(amd_spi_driver);
MODULE_LICENSE("Dual BSD/GPL");
MODULE_AUTHOR("Sanjay Mehta <sanju.mehta@amd.com>");
MODULE_DESCRIPTION("AMD SPI Master Controller Driver");
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