Re: [PATCH 2/2] w1: Add 1-wire master driver for AMD programmable logic IP Core

Kris Chaplin
2023-10-18T15:54:46Z

Thank you Krzysztof,

I shall post v2 tomorrow:

On 13/10/2023 16:20, Krzysztof Kozlowski wrote:
> On 13/10/2023 11:30, Kris Chaplin wrote:
>> Add a master driver to support the AMD 1-Wire programmable logic IP block.
>> This block guarantees protocol timing for driving off-board devices such
>> as thermal sensors, proms, etc.
>>
>> Add file to MAINTAINERS
>>
>> Co-developed-by: Thomas Delev <thomas.delev@amd.com>
>> Signed-off-by: Thomas Delev <thomas.delev@amd.com>
>> Signed-off-by: Kris Chaplin <kris.chaplin@amd.com>
>> ---
>> MAINTAINERS | 1 +
>> drivers/w1/masters/Kconfig | 11 +
>> drivers/w1/masters/Makefile | 1 +
>> drivers/w1/masters/amd_w1.c | 422 ++++++++++++++++++++++++++++++++++++
>> 4 files changed, 435 insertions(+)
>> create mode 100644 drivers/w1/masters/amd_w1.c
>>
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index 6ec3922b256e..7f26dab5261b 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -1072,6 +1072,7 @@ R: Thomas Delev <thomas.delev@amd.com>
>> R: Michal Simek <michal.simek@amd.com>
>> S: Maintained
>> F: Documentation/devicetree/bindings/w1/amd,axi-1wire-master.yaml
>> +F: drivers/w1/masters/amd_w1.c
>>
>> AMD XGBE DRIVER
>> M: "Shyam Sundar S K" <Shyam-sundar.S-k@amd.com>
>> diff --git a/drivers/w1/masters/Kconfig b/drivers/w1/masters/Kconfig
>> index ad316573288a..9232fd1f4e5b 100644
>> --- a/drivers/w1/masters/Kconfig
>> +++ b/drivers/w1/masters/Kconfig
>> @@ -67,5 +67,16 @@ config W1_MASTER_SGI
>> This support is also available as a module. If so, the module
>> will be called sgi_w1.
>>
>> +config W1_MASTER_AMD
> This looks oddly places. Isn't entry above 'S', so A should go before?
> The rule is for entire Linux kernel: do not stuff things to the end of
> the lists.
There doesnt appear to be a specific alphabetical ordering taking place
in this Kconfig:

config W1_MASTER_MATROX
config W1_MASTER_DS2490
config W1_MASTER_DS2482
config W1_MASTER_MXC
config W1_MASTER_GPIO
config HDQ_MASTER_OMAP
config W1_MASTER_SGI
config W1_MASTER_AMD

I've moved AMD to the top of Kconfig for v2.  If appropriate, please
advise and I'll send in a pair of patches for Makefile and Kconfig to
reorder alpahbetically separate to this patch set.

>> + tristate "AMD AXI 1-wire bus master"
>> + help
>> + Say Y here is you want to support the AMD AXI 1-wire IP core.
>> + This driver makes use of the programmable logic IP to perform
>> + correctly timed 1 wire transactions without relying on GPIO timing
>> + through the kernel.
>> +
>> + This driver can also be built as a module. If so, the module will be
>> + called amd_w1.
>> +
>> endmenu
>>
>> diff --git a/drivers/w1/masters/Makefile b/drivers/w1/masters/Makefile
>> index c5d85a827e52..cd3da1daaf97 100644
>> --- a/drivers/w1/masters/Makefile
>> +++ b/drivers/w1/masters/Makefile
>> @@ -11,3 +11,4 @@ obj-$(CONFIG_W1_MASTER_MXC) += mxc_w1.o
>> obj-$(CONFIG_W1_MASTER_GPIO) += w1-gpio.o
>> obj-$(CONFIG_HDQ_MASTER_OMAP) += omap_hdq.o
>> obj-$(CONFIG_W1_MASTER_SGI) += sgi_w1.o
>> +obj-$(CONFIG_W1_MASTER_AMD) += amd_w1.o
>> diff --git a/drivers/w1/masters/amd_w1.c b/drivers/w1/masters/amd_w1.c
>> new file mode 100644
>> index 000000000000..04bf08c1b6d7
>> --- /dev/null
>> +++ b/drivers/w1/masters/amd_w1.c
>> @@ -0,0 +1,422 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/*
>> + * amd_w1 - AMD 1Wire bus master 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_w1"
>> +
>> +struct amd_w1_local {
>> + struct device *dev;
>> + void __iomem *base_addr;
>> + int irq;
>> + atomic_t flag;
> Document what this flag does and what its purpose.
Done for v2
>> + struct clk *clk;
> Why do you need this? It's never changed (after fixing the bug).
Removed in v2
>
>> + wait_queue_head_t wait_queue;
>> +};
>> +
>> +/**
>> + * amd_w1_write_register() - Helper to write a hardware register.
>> + *
>> + * @amd_w1_local: Pointer to device structure
>> + * @reg_offset: Register offset in bytes to write
>> + * @val: Value to write
>> + */
>> +static inline void amd_w1_write_register(struct amd_w1_local *amd_w1_local,
>> + u8 reg_offset, u32 val)
>> +{
>> + iowrite32(val, amd_w1_local->base_addr + reg_offset);
> Unwrapped code:
> iowrite32(IRQ, amd_w1_local->base_addr + AXIW1_IRQE_REG);
>
> Your wrapper:
> amd_w1_write_register(amd_w1_local, AXIW1_IRQE_REG, IRQ);
>
> Does not look simpler. If you want to use wrappers, they should actually
> help.
Unwrapped in v2
>
>> +};
>> +
>> +/**
>> + * amd_w1_read_register() - Helper to write a hardware register.
>> + *
>> + * @amd_w1_local: Pointer to device structure
>> + * @reg_offset: Register offset in bytes to write
>> + *
>> + * Return: Value of register read
>> + */
>> +static inline u32 amd_w1_read_register(struct amd_w1_local *amd_w1_local, u8 reg_offset)
>> +{
>> + return ioread32(amd_w1_local->base_addr + reg_offset);
>> +};
>> +
>> +/**
>> + * amd_w1_wait_irq_interruptible_timeout() - Wait for IRQ with timeout.
>> + *
>> + * @amd_w1_local: Pointer to device structure
>> + * @IRQ: IRQ channel to wait on
>> + *
>> + * Return: %0 - OK, %-EINTR - Interrupted, %-EBUSY - Timed out
>> + */
>> +static inline int amd_w1_wait_irq_interruptible_timeout(struct amd_w1_local *amd_w1_local, u32 IRQ)
> Drop inline.
> This does not look like wrapped according to Linux coding convention.
> Please abide by the convention, so wrap at 80.
Inline dropped.  I've wrapped it in v2, albeit at column 84 as that is
the first break point (comma).
>
>> +{
>> + int ret;
>> +
>> + /* Enable the IRQ requested and wait for flag to indicate it's been triggered */
>> + amd_w1_write_register(amd_w1_local, AXIW1_IRQE_REG, IRQ);
>> + ret = wait_event_interruptible_timeout(amd_w1_local->wait_queue,
>> + atomic_read(&amd_w1_local->flag) != 0,
>> + AXIW1_TIMEOUT);
>> + if (ret < 0) {
>> + dev_err(amd_w1_local->dev, "Wait IRQ Interrupted\n");
>> + return -EINTR;
>> + }
>> +
>> + if (!ret) {
>> + dev_err(amd_w1_local->dev, "Wait IRQ Timeout\n");
>> + return -EBUSY;
>> + }
>> +
>> + /* Clear flag */
> Drop.
Dropped in v2
>
>> + atomic_set(&amd_w1_local->flag, 0);
>> + return 0;
>> +}
>> +
>> +/**
>> + * amd_w1_touch_bit() - Performs the touch-bit function, which writes 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_w1_touch_bit(void *data, u8 bit)
>> +{
>> + struct amd_w1_local *amd_w1_local = data;
>> + u8 val = 0;
>> + int rc;
>> +
>> + /* Wait for READY signal to be 1 to ensure 1-wire IP is ready */
>> + while ((amd_w1_read_register(amd_w1_local, AXIW1_STAT_REG) & AXIW1_READY) == 0) {
>> + rc = amd_w1_wait_irq_interruptible_timeout(amd_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 */
>> + amd_w1_write_register(amd_w1_local, AXIW1_INST_REG, AXIW1_READBIT);
>> + else
>> + /* Write. Write tx Bit command in instruction register with bit to transmit */
>> + amd_w1_write_register(amd_w1_local, AXIW1_INST_REG,
>> + (AXIW1_WRITEBIT + (bit & 0x01)));
>> +
>> + /* Write Go signal and clear control reset signal in control register */
>> + amd_w1_write_register(amd_w1_local, AXIW1_CTRL_REG, AXIW1_GO);
>> +
>> + /* Wait for done signal to be 1 */
>> + while ((amd_w1_read_register(amd_w1_local, AXIW1_STAT_REG) & AXIW1_DONE) != 1) {
>> + rc = amd_w1_wait_irq_interruptible_timeout(amd_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)(amd_w1_read_register(amd_w1_local, AXIW1_DATA_REG) & AXIW1_READDATA);
>> +
>> + /* Clear Go signal in register 1 */
>> + amd_w1_write_register(amd_w1_local, AXIW1_CTRL_REG, AXI_CLEAR);
>> +
>> + return val;
>> +}
>> +
>> +/**
>> + * amd_w1_read_byte - Performs the read byte function.
>> + *
>> + * @data: Pointer to device structure
>> + * Return: The value read
>> + */
>> +static u8 amd_w1_read_byte(void *data)
>> +{
>> + struct amd_w1_local *amd_w1_local = data;
>> + u8 val = 0;
>> + int rc;
>> +
>> + /* Wait for READY signal to be 1 to ensure 1-wire IP is ready */
>> + while ((amd_w1_read_register(amd_w1_local, AXIW1_STAT_REG) & AXIW1_READY) == 0) {
>> + rc = amd_w1_wait_irq_interruptible_timeout(amd_w1_local, AXIW1_READY_IRQ_EN);
>> + if (rc < 0)
>> + return 0xFF; /* Return inactive bus state */
>> + }
>> +
>> + /* Write read Byte command in instruction register*/
>> + amd_w1_write_register(amd_w1_local, AXIW1_INST_REG, AXIW1_READBYTE);
>> + /* Write Go signal and clear control reset signal in control register */
>> + amd_w1_write_register(amd_w1_local, AXIW1_CTRL_REG, AXIW1_GO);
>> +
>> + /* Wait for done signal to be 1 */
>> + while ((amd_w1_read_register(amd_w1_local, AXIW1_STAT_REG) & AXIW1_DONE) != 1) {
>> + rc = amd_w1_wait_irq_interruptible_timeout(amd_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)(amd_w1_read_register(amd_w1_local, AXIW1_DATA_REG) & 0x000000FF);
>> +
>> + /* Clear Go signal in control register */
>> + amd_w1_write_register(amd_w1_local, AXIW1_CTRL_REG, AXI_CLEAR);
>> +
>> + return val;
>> +}
>> +
>> +/**
>> + * amd_w1_write_byte - Performs the write byte function.
>> + *
>> + * @data: The ds2482 channel pointer
>> + * @val: The value to write
>> + */
>> +static void amd_w1_write_byte(void *data, u8 val)
>> +{
>> + struct amd_w1_local *amd_w1_local = data;
>> + int rc;
>> +
>> + /* Wait for READY signal to be 1 to ensure 1-wire IP is ready */
>> + while ((amd_w1_read_register(amd_w1_local, AXIW1_STAT_REG) & AXIW1_READY) == 0) {
>> + rc = amd_w1_wait_irq_interruptible_timeout(amd_w1_local, AXIW1_READY_IRQ_EN);
>> + if (rc < 0)
>> + return;
>> + }
>> +
>> + /* Write tx Byte command in instruction register with bit to transmit */
>> + amd_w1_write_register(amd_w1_local, AXIW1_INST_REG, (AXIW1_WRITEBYTE + val));
>> + /* Write Go signal and clear control reset signal in register 1 */
>> + amd_w1_write_register(amd_w1_local, AXIW1_CTRL_REG, AXIW1_GO);
>> +
>> + /* Wait for done signal to be 1 */
>> + while ((amd_w1_read_register(amd_w1_local, AXIW1_STAT_REG) & AXIW1_DONE) != 1) {
>> + rc = amd_w1_wait_irq_interruptible_timeout(amd_w1_local, AXIW1_DONE_IRQ_EN);
>> + if (rc < 0)
>> + return;
>> + }
>> +
>> + /* Clear Go signal in control register */
>> + amd_w1_write_register(amd_w1_local, AXIW1_CTRL_REG, AXI_CLEAR);
>> +}
>> +
>> +/**
>> + * amd_w1_reset_bus() - Issues a reset bus sequence.
>> + *
>> + * @data: the bus master data struct
>> + * Return: 0=Device present, 1=No device present or error
>> + */
>> +static u8 amd_w1_reset_bus(void *data)
>> +{
>> + struct amd_w1_local *amd_w1_local = data;
>> + u8 val = 0;
>> + int rc;
>> +
>> + /* Reset 1-wire Axi IP */
>> + amd_w1_write_register(amd_w1_local, AXIW1_CTRL_REG, AXI_RESET);
>> +
>> + /* Wait for READY signal to be 1 to ensure 1-wire IP is ready */
>> + while ((amd_w1_read_register(amd_w1_local, AXIW1_STAT_REG) & AXIW1_READY) == 0) {
>> + rc = amd_w1_wait_irq_interruptible_timeout(amd_w1_local, AXIW1_READY_IRQ_EN);
>> + if (rc < 0)
>> + return 1; /* Something went wrong with the hardware */
>> + }
>> + /* Write Initialization command in instruction register */
>> + amd_w1_write_register(amd_w1_local, AXIW1_INST_REG, AXIW1_INITPRES);
>> + /* Write Go signal and clear control reset signal in register 1 */
>> + amd_w1_write_register(amd_w1_local, AXIW1_CTRL_REG, AXIW1_GO);
>> +
>> + /* Wait for done signal to be 1 */
>> + while ((amd_w1_read_register(amd_w1_local, AXIW1_STAT_REG) & AXIW1_DONE) != 1) {
>> + rc = amd_w1_wait_irq_interruptible_timeout(amd_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 ((amd_w1_read_register(amd_w1_local, AXIW1_STAT_REG) & AXIW1_PRESENCE) != 0)
>> + val = 1;
>> +
>> + /* Clear Go signal in control register */
>> + amd_w1_write_register(amd_w1_local, AXIW1_CTRL_REG, AXI_CLEAR);
>> +
>> + return val;
>> +}
>> +
>> +/* 1-wire master structure */
>> +static struct w1_bus_master amd_w1_master = {
> And how does it work with two devices?
Thanks - we've got a 2x instance design running and I've reproduced an
issue with rmmod on cleanup when both are active.  Fixed and will submit
in v2.
>
>> + .touch_bit = amd_w1_touch_bit,
>> + .read_byte = amd_w1_read_byte,
>> + .write_byte = amd_w1_write_byte,
>> + .reset_bus = amd_w1_reset_bus,
>> +};
>> +
>> +/* Reset the 1-wire AXI IP. Put the IP in reset state and clear registers */
>> +static void amd_w1_reset(struct amd_w1_local *amd_w1_local)
>> +{
>> + amd_w1_write_register(amd_w1_local, AXIW1_CTRL_REG, AXI_RESET);
>> + amd_w1_write_register(amd_w1_local, AXIW1_INST_REG, AXI_CLEAR);
>> + amd_w1_write_register(amd_w1_local, AXIW1_IRQE_REG, AXI_CLEAR);
>> + amd_w1_write_register(amd_w1_local, AXIW1_STAT_REG, AXI_CLEAR);
>> + amd_w1_write_register(amd_w1_local, AXIW1_DATA_REG, AXI_CLEAR);
>> +}
>> +
>> +static irqreturn_t amd_w1_irq(int irq, void *lp)
>> +{
>> + struct amd_w1_local *amd_w1_local = lp;
>> +
>> + /* Clear enables in IRQ enable register */
> I don't understand this comment.
Reworded in v2 to "Reset interrupt trigger"
>
>> + amd_w1_write_register(amd_w1_local, AXIW1_IRQE_REG, AXI_CLEAR);
>> +
>> + /* Wake up the waiting queue */
>
> Drop obvious comments.
Done in v2
>
>> + atomic_set(&amd_w1_local->flag, 1);
>> + wake_up_interruptible(&amd_w1_local->wait_queue);
>> +
>> + return IRQ_HANDLED;
>> +}
>> +
>> +static int amd_w1_probe(struct platform_device *pdev)
>> +{
>> + struct device *dev = &pdev->dev;
>> + struct amd_w1_local *lp;
>> + u32 ver_major, ver_minor;
>> + int val, rc = 0;
>> +
>> + /* Get iospace for the device */
> This is memory allocation, not IO space.
Agree - Dropped in v2 with other obvious comments
>> + 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);
>> +
>> + /* Get IRQ for the device */
> Drop obvious comments.
Dropped in v2
>
>> + lp->irq = platform_get_irq(pdev, 0);
>> + if (lp->irq <= 0)
> Open platform_get_irq() function and read the help. Error handling
> couldn't be more explicit there...
Changed in v2
>
>> + return lp->irq;
>> +
>> + rc = devm_request_irq(dev, lp->irq, &amd_w1_irq, IRQF_TRIGGER_HIGH, DRIVER_NAME, lp);
>> + if (rc) {
>> + dev_err(dev, "Could not allocate interrupt %d.\n", lp->irq);
> return dev_err_probe(). But this leads us to second question: why would
> you notify about allocation errors? Core does it. Do you mean request?
I did mean request - removed dev_err for return in v2.
>> + return rc;
>> + }
>> +
>> + /* Initialize wait queue and flag */
>> + init_waitqueue_head(&lp->wait_queue);
>> +
>> + lp->clk = devm_clk_get_enabled(dev, NULL);
>> + if (IS_ERR(lp->clk))
>> + return PTR_ERR(lp->clk);
>> +
>> + /* Verify IP presence in HW */
>> + if (amd_w1_read_register(lp, 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 = amd_w1_read_register(lp, 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 Master version %u.%u is not supported by this driver",
>> + ver_major, ver_minor);
>> + return -ENODEV;
>> + }
>> +
>> + amd_w1_master.data = (void *)lp;
>> + amd_w1_reset(lp);
>> +
>> + platform_set_drvdata(pdev, lp);
>> + rc = w1_add_master_device(&amd_w1_master);
>> + if (rc) {
>> + dev_err(dev, "Could not add master device\n");
>> + amd_w1_reset(lp);
> Why? Does this mean that w1_add_master_device() changes the state of
> hardware?
No it doesnt - removed un-needed reset in v2.
>
>> + return rc;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static void amd_w1_remove(struct platform_device *pdev)
>> +{
>> + struct amd_w1_local *lp = platform_get_drvdata(pdev);
>> +
>> + w1_remove_master_device(&amd_w1_master);
>> + clk_disable_unprepare(lp->clk);
> This wasn't tested. Duplicated disable.
Thank you.  Bug reproduced with rmmod on module version of driver and
resolved in v2.
>
>> +}
>> +
>> +static const struct of_device_id amd_w1_of_match[] = {
>> + { .compatible = "amd,axi-1wire-master" },
>> + { /* end of list */ },
>> +};
>> +MODULE_DEVICE_TABLE(of, amd_w1_of_match);
>> +
>> +static struct platform_driver amd_w1_driver = {
>> + .probe = amd_w1_probe,
>> + .remove_new = amd_w1_remove,
>> + .driver = {
>> + .name = DRIVER_NAME,
>> + .of_match_table = amd_w1_of_match,
>> + },
>> +};
>> +module_platform_driver(amd_w1_driver);
>> +
>> +MODULE_LICENSE("GPL");
>> +MODULE_AUTHOR("Kris Chaplin <kris.chaplin@amd.com>");
>> +MODULE_DESCRIPTION("Driver for AMD AXI 1 Wire IP core");
> Best regards,
> Krzysztof

Regards,
Kris