--- /dev/null
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * amd_axi_w1 - AMD 1Wire programmable logic bus host driver
+ *
+ * Copyright (C) 2022-2023 Advanced Micro Devices, Inc. All Rights Reserved.
+ */
+
+#include <linux/atomic.h>
+#include <linux/bitfield.h>
+#include <linux/clk.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/jiffies.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of_platform.h>
+#include <linux/types.h>
+#include <linux/wait.h>
+
+#include <linux/w1.h>
+
+/* 1-wire AMD IP definition */
+#define AXIW1_IPID 0x10ee4453
+/* Registers offset */
+#define AXIW1_INST_REG 0x0
+#define AXIW1_CTRL_REG 0x4
+#define AXIW1_IRQE_REG 0x8
+#define AXIW1_STAT_REG 0xC
+#define AXIW1_DATA_REG 0x10
+#define AXIW1_IPVER_REG 0x18
+#define AXIW1_IPID_REG 0x1C
+/* Instructions */
+#define AXIW1_INITPRES 0x0800
+#define AXIW1_READBIT 0x0C00
+#define AXIW1_WRITEBIT 0x0E00
+#define AXIW1_READBYTE 0x0D00
+#define AXIW1_WRITEBYTE 0x0F00
+/* Status flag masks */
+#define AXIW1_DONE BIT(0)
+#define AXIW1_READY BIT(4)
+#define AXIW1_PRESENCE BIT(31)
+#define AXIW1_MAJORVER_MASK GENMASK(23, 8)
+#define AXIW1_MINORVER_MASK GENMASK(7, 0)
+/* Control flag */
+#define AXIW1_GO BIT(0)
+#define AXI_CLEAR 0
+#define AXI_RESET BIT(31)
+#define AXIW1_READDATA BIT(0)
+/* Interrupt Enable */
+#define AXIW1_READY_IRQ_EN BIT(4)
+#define AXIW1_DONE_IRQ_EN BIT(0)
+
+#define AXIW1_TIMEOUT msecs_to_jiffies(100)
+
+#define DRIVER_NAME "amd_axi_w1"
+
+struct amd_axi_w1_local {
+ struct device *dev;
+ void __iomem *base_addr;
+ int irq;
+ atomic_t flag; /* Set on IRQ, cleared once serviced */
+ wait_queue_head_t wait_queue;
+ struct w1_bus_master bus_host;
+};
+
+/**
+ * amd_axi_w1_wait_irq_interruptible_timeout() - Wait for IRQ with timeout.
+ *
+ * @amd_axi_w1_local: Pointer to device structure
+ * @IRQ: IRQ channel to wait on
+ *
+ * Return: %0 - OK, %-EINTR - Interrupted, %-EBUSY - Timed out
+ */
+static int amd_axi_w1_wait_irq_interruptible_timeout(struct amd_axi_w1_local *amd_axi_w1_local,
+ u32 IRQ)
+{
+ int ret;
+
+ /* Enable the IRQ requested and wait for flag to indicate it's been triggered */
+ iowrite32(IRQ, amd_axi_w1_local->base_addr + AXIW1_IRQE_REG);
+ ret = wait_event_interruptible_timeout(amd_axi_w1_local->wait_queue,
+ atomic_read(&amd_axi_w1_local->flag) != 0,
+ AXIW1_TIMEOUT);
+ if (ret < 0) {
+ dev_err(amd_axi_w1_local->dev, "Wait IRQ Interrupted\n");
+ return -EINTR;
+ }
+
+ if (!ret) {
+ dev_err(amd_axi_w1_local->dev, "Wait IRQ Timeout\n");
+ return -EBUSY;
+ }
+
+ atomic_set(&amd_axi_w1_local->flag, 0);
+ return 0;
+}
+
+/**
+ * amd_axi_w1_touch_bit() - Performs the touch-bit function - write a 0 or 1 and reads the level.
+ *
+ * @data: Pointer to device structure
+ * @bit: The level to write
+ *
+ * Return: The level read
+ */
+static u8 amd_axi_w1_touch_bit(void *data, u8 bit)
+{
+ struct amd_axi_w1_local *amd_axi_w1_local = data;
+ u8 val = 0;
+ int rc;
+
+ /* Wait for READY signal to be 1 to ensure 1-wire IP is ready */
+ while ((ioread32(amd_axi_w1_local->base_addr + AXIW1_STAT_REG) & AXIW1_READY) == 0) {
+ rc = amd_axi_w1_wait_irq_interruptible_timeout(amd_axi_w1_local,
+ AXIW1_READY_IRQ_EN);
+ if (rc < 0)
+ return 1; /* Callee doesn't test for error. Return inactive bus state */
+ }
+
+ if (bit)
+ /* Read. Write read Bit command in register 0 */
+ iowrite32(AXIW1_READBIT, amd_axi_w1_local->base_addr + AXIW1_INST_REG);
+ else
+ /* Write. Write tx Bit command in instruction register with bit to transmit */
+ iowrite32(AXIW1_WRITEBIT + (bit & 0x01),
+ amd_axi_w1_local->base_addr + AXIW1_INST_REG);
+
+ /* Write Go signal and clear control reset signal in control register */
+ iowrite32(AXIW1_GO, amd_axi_w1_local->base_addr + AXIW1_CTRL_REG);
+
+ /* Wait for done signal to be 1 */
+ while ((ioread32(amd_axi_w1_local->base_addr + AXIW1_STAT_REG) & AXIW1_DONE) != 1) {
+ rc = amd_axi_w1_wait_irq_interruptible_timeout(amd_axi_w1_local, AXIW1_DONE_IRQ_EN);
+ if (rc < 0)
+ return 1; /* Callee doesn't test for error. Return inactive bus state */
+ }
+
+ /* If read, Retrieve data from register */
+ if (bit)
+ val = (u8)(ioread32(amd_axi_w1_local->base_addr + AXIW1_DATA_REG) & AXIW1_READDATA);
+
+ /* Clear Go signal in register 1 */
+ iowrite32(AXI_CLEAR, amd_axi_w1_local->base_addr + AXIW1_CTRL_REG);
+
+ return val;
+}
+
+/**
+ * amd_axi_w1_read_byte - Performs the read byte function.
+ *
+ * @data: Pointer to device structure
+ * Return: The value read
+ */
+static u8 amd_axi_w1_read_byte(void *data)
+{
+ struct amd_axi_w1_local *amd_axi_w1_local = data;
+ u8 val = 0;
+ int rc;
+
+ /* Wait for READY signal to be 1 to ensure 1-wire IP is ready */
+ while ((ioread32(amd_axi_w1_local->base_addr + AXIW1_STAT_REG) & AXIW1_READY) == 0) {
+ rc = amd_axi_w1_wait_irq_interruptible_timeout(amd_axi_w1_local,
+ AXIW1_READY_IRQ_EN);
+ if (rc < 0)
+ return 0xFF; /* Return inactive bus state */
+ }
+
+ /* Write read Byte command in instruction register*/
+ iowrite32(AXIW1_READBYTE, amd_axi_w1_local->base_addr + AXIW1_INST_REG);
+
+ /* Write Go signal and clear control reset signal in control register */
+ iowrite32(AXIW1_GO, amd_axi_w1_local->base_addr + AXIW1_CTRL_REG);
+
+ /* Wait for done signal to be 1 */
+ while ((ioread32(amd_axi_w1_local->base_addr + AXIW1_STAT_REG) & AXIW1_DONE) != 1) {
+ rc = amd_axi_w1_wait_irq_interruptible_timeout(amd_axi_w1_local, AXIW1_DONE_IRQ_EN);
+ if (rc < 0)
+ return 0xFF; /* Return inactive bus state */
+ }
+
+ /* Retrieve LSB bit in data register to get RX byte */
+ val = (u8)(ioread32(amd_axi_w1_local->base_addr + AXIW1_DATA_REG) & 0x000000FF);
+
+ /* Clear Go signal in control register */
+ iowrite32(AXI_CLEAR, amd_axi_w1_local->base_addr + AXIW1_CTRL_REG);
+
+ return val;
+}
+
+/**
+ * amd_axi_w1_write_byte - Performs the write byte function.
+ *
+ * @data: The ds2482 channel pointer
+ * @val: The value to write
+ */
+static void amd_axi_w1_write_byte(void *data, u8 val)
+{
+ struct amd_axi_w1_local *amd_axi_w1_local = data;
+ int rc;
+
+ /* Wait for READY signal to be 1 to ensure 1-wire IP is ready */
+ while ((ioread32(amd_axi_w1_local->base_addr + AXIW1_STAT_REG) & AXIW1_READY) == 0) {
+ rc = amd_axi_w1_wait_irq_interruptible_timeout(amd_axi_w1_local,
+ AXIW1_READY_IRQ_EN);
+ if (rc < 0)
+ return;
+ }
+
+ /* Write tx Byte command in instruction register with bit to transmit */
+ iowrite32(AXIW1_WRITEBYTE + val, amd_axi_w1_local->base_addr + AXIW1_INST_REG);
+
+ /* Write Go signal and clear control reset signal in register 1 */
+ iowrite32(AXIW1_GO, amd_axi_w1_local->base_addr + AXIW1_CTRL_REG);
+
+ /* Wait for done signal to be 1 */
+ while ((ioread32(amd_axi_w1_local->base_addr + AXIW1_STAT_REG) & AXIW1_DONE) != 1) {
+ rc = amd_axi_w1_wait_irq_interruptible_timeout(amd_axi_w1_local,
+ AXIW1_DONE_IRQ_EN);
+ if (rc < 0)
+ return;
+ }
+
+ /* Clear Go signal in control register */
+ iowrite32(AXI_CLEAR, amd_axi_w1_local->base_addr + AXIW1_CTRL_REG);
+}
+
+/**
+ * amd_axi_w1_reset_bus() - Issues a reset bus sequence.
+ *
+ * @data: the bus host data struct
+ * Return: 0=Device present, 1=No device present or error
+ */
+static u8 amd_axi_w1_reset_bus(void *data)
+{
+ struct amd_axi_w1_local *amd_axi_w1_local = data;
+ u8 val = 0;
+ int rc;
+
+ /* Reset 1-wire Axi IP */
+ iowrite32(AXI_RESET, amd_axi_w1_local->base_addr + AXIW1_CTRL_REG);
+
+ /* Wait for READY signal to be 1 to ensure 1-wire IP is ready */
+ while ((ioread32(amd_axi_w1_local->base_addr + AXIW1_STAT_REG) & AXIW1_READY) == 0) {
+ rc = amd_axi_w1_wait_irq_interruptible_timeout(amd_axi_w1_local,
+ AXIW1_READY_IRQ_EN);
+ if (rc < 0)
+ return 1; /* Something went wrong with the hardware */
+ }
+ /* Write Initialization command in instruction register */
+ iowrite32(AXIW1_INITPRES, amd_axi_w1_local->base_addr + AXIW1_INST_REG);
+
+ /* Write Go signal and clear control reset signal in register 1 */
+ iowrite32(AXIW1_GO, amd_axi_w1_local->base_addr + AXIW1_CTRL_REG);
+
+ /* Wait for done signal to be 1 */
+ while ((ioread32(amd_axi_w1_local->base_addr + AXIW1_STAT_REG) & AXIW1_DONE) != 1) {
+ rc = amd_axi_w1_wait_irq_interruptible_timeout(amd_axi_w1_local, AXIW1_DONE_IRQ_EN);
+ if (rc < 0)
+ return 1; /* Something went wrong with the hardware */
+ }
+ /* Retrieve MSB bit in status register to get failure bit */
+ if ((ioread32(amd_axi_w1_local->base_addr + AXIW1_STAT_REG) & AXIW1_PRESENCE) != 0)
+ val = 1;
+
+ /* Clear Go signal in control register */
+ iowrite32(AXI_CLEAR, amd_axi_w1_local->base_addr + AXIW1_CTRL_REG);
+
+ return val;
+}
+
+/* Reset the 1-wire AXI IP. Put the IP in reset state and clear registers */
+static void amd_axi_w1_reset(struct amd_axi_w1_local *amd_axi_w1_local)
+{
+ iowrite32(AXI_RESET, amd_axi_w1_local->base_addr + AXIW1_CTRL_REG);
+ iowrite32(AXI_CLEAR, amd_axi_w1_local->base_addr + AXIW1_INST_REG);
+ iowrite32(AXI_CLEAR, amd_axi_w1_local->base_addr + AXIW1_IRQE_REG);
+ iowrite32(AXI_CLEAR, amd_axi_w1_local->base_addr + AXIW1_STAT_REG);
+ iowrite32(AXI_CLEAR, amd_axi_w1_local->base_addr + AXIW1_DATA_REG);
+}
+
+static irqreturn_t amd_axi_w1_irq(int irq, void *lp)
+{
+ struct amd_axi_w1_local *amd_axi_w1_local = lp;
+
+ /* Reset interrupt trigger */
+ iowrite32(AXI_CLEAR, amd_axi_w1_local->base_addr + AXIW1_IRQE_REG);
+
+ atomic_set(&amd_axi_w1_local->flag, 1);
+ wake_up_interruptible(&amd_axi_w1_local->wait_queue);
+
+ return IRQ_HANDLED;
+}
+
+static int amd_axi_w1_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct amd_axi_w1_local *lp;
+ struct clk *clk;
+ u32 ver_major, ver_minor;
+ int val, rc = 0;
+
+ lp = devm_kzalloc(dev, sizeof(*lp), GFP_KERNEL);
+ if (!lp)
+ return -ENOMEM;
+
+ lp->dev = dev;
+ lp->base_addr = devm_platform_ioremap_resource(pdev, 0);
+ if (IS_ERR(lp->base_addr))
+ return PTR_ERR(lp->base_addr);
+
+ lp->irq = platform_get_irq(pdev, 0);
+ if (lp->irq < 0)
+ return lp->irq;
+
+ rc = devm_request_irq(dev, lp->irq, &amd_axi_w1_irq, IRQF_TRIGGER_HIGH, DRIVER_NAME, lp);
+ if (rc)
+ return rc;
+
+ /* Initialize wait queue and flag */
+ init_waitqueue_head(&lp->wait_queue);
+
+ clk = devm_clk_get_enabled(dev, NULL);
+ if (IS_ERR(clk))
+ return PTR_ERR(clk);
+
+ /* Verify IP presence in HW */
+ if (ioread32(lp->base_addr + AXIW1_IPID_REG) != AXIW1_IPID) {
+ dev_err(dev, "AMD 1-wire IP not detected in hardware\n");
+ return -ENODEV;
+ }
+
+ /*
+ * Allow for future driver expansion supporting new hardware features
+ * This driver currently only supports hardware 1.x, but include logic
+ * to detect if a potentially incompatible future version is used
+ * by reading major version ID. It is highly undesirable for new IP versions
+ * to break the API, but this code will at least allow for graceful failure
+ * should that happen. Future new features can be enabled by hardware
+ * incrementing the minor version and augmenting the driver to detect capability
+ * using the minor version number
+ */
+ val = ioread32(lp->base_addr + AXIW1_IPVER_REG);
+ ver_major = FIELD_GET(AXIW1_MAJORVER_MASK, val);
+ ver_minor = FIELD_GET(AXIW1_MINORVER_MASK, val);
+
+ if (ver_major != 1) {
+ dev_err(dev, "AMD AXI W1 host version %u.%u is not supported by this driver",
+ ver_major, ver_minor);
+ return -ENODEV;
+ }
+
+ lp->bus_host.data = lp;
+ lp->bus_host.touch_bit = amd_axi_w1_touch_bit;
+ lp->bus_host.read_byte = amd_axi_w1_read_byte;
+ lp->bus_host.write_byte = amd_axi_w1_write_byte;
+ lp->bus_host.reset_bus = amd_axi_w1_reset_bus;
+
+ amd_axi_w1_reset(lp);
+
+ platform_set_drvdata(pdev, lp);
+ rc = w1_add_master_device(&lp->bus_host);
+ if (rc) {
+ dev_err(dev, "Could not add host device\n");
+ return rc;
+ }
+
+ return 0;
+}
+
+static void amd_axi_w1_remove(struct platform_device *pdev)
+{
+ struct amd_axi_w1_local *lp = platform_get_drvdata(pdev);
+
+ w1_remove_master_device(&lp->bus_host);
+}
+
+static const struct of_device_id amd_axi_w1_of_match[] = {
+ { .compatible = "amd,axi-1wire-host" },
+ { /* end of list */ },
+};
+MODULE_DEVICE_TABLE(of, amd_axi_w1_of_match);
+
+static struct platform_driver amd_axi_w1_driver = {
+ .probe = amd_axi_w1_probe,
+ .remove_new = amd_axi_w1_remove,
+ .driver = {
+ .name = DRIVER_NAME,
+ .of_match_table = amd_axi_w1_of_match,
+ },
+};
+module_platform_driver(amd_axi_w1_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Kris Chaplin <kris.chaplin@amd.com>");
+MODULE_DESCRIPTION("Driver for AMD AXI 1 Wire IP core");
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