Re: [PATCH V2 2/2] i3c: master: Add AMD I3C bus controller driver

Frank Li
2025-09-03T19:18:51Z

On Fri, Aug 29, 2025 at 10:43:27PM +0530, Manikanta Guntupalli wrote:
> Add an I3C master driver and maintainers fragment for the AMD I3C bus
> controller.
>
> The driver currently supports the I3C bus operating in SDR i3c mode,
> with features including Dynamic Address Assignment, private data transfers,
> and CCC transfers in both broadcast and direct modes. It also supports
> operation in I2C mode.
>
> Signed-off-by: Manikanta Guntupalli <manikanta.guntupalli@amd.com>
> ---
> Changes for V2:
> Updated commit description.
> Added mixed mode support with clock configuration.
> Converted smaller functions into inline functions.
> Used FIELD_GET() in xi3c_get_response().
> Updated xi3c_master_rd_from_rx_fifo() to use cmd->rx_buf.
> Used parity8() for address parity calculation.
> Added guards for locks.
> Dropped num_targets and updated xi3c_master_do_daa().
> Used __free(kfree) in xi3c_master_send_bdcast_ccc_cmd().
> Dropped PM runtime support.
> Updated xi3c_master_read() and xi3c_master_write() with
> xi3c_is_resp_available() check.
> Created separate functions: xi3c_master_init() and xi3c_master_reinit().
> Used xi3c_master_init() in bus initialization and xi3c_master_reinit()
> in error paths.
> Added DAA structure to xi3c_master structure.
> ---
> MAINTAINERS | 7 +
> drivers/i3c/master/Kconfig | 16 +
> drivers/i3c/master/Makefile | 1 +
> drivers/i3c/master/amd-i3c-master.c | 1009 +++++++++++++++++++++++++++
> 4 files changed, 1033 insertions(+)
> create mode 100644 drivers/i3c/master/amd-i3c-master.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 0cb9e55021cb..28ee1554cb0b 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -11416,6 +11416,13 @@ L: linux-i2c@vger.kernel.org
> S: Maintained
> F: drivers/i2c/i2c-stub.c
>
> +I3C DRIVER FOR AMD AXI I3C MASTER
> +M: Manikanta Guntupalli <manikanta.guntupalli@amd.com>
> +R: Michal Simek <michal.simek@amd.com>
> +S: Maintained
> +F: Documentation/devicetree/bindings/i3c/xlnx,axi-i3c.yaml
> +F: drivers/i3c/master/amd-i3c-master.c
> +
> I3C DRIVER FOR ASPEED AST2600
> M: Jeremy Kerr <jk@codeconstruct.com.au>
> S: Maintained
> diff --git a/drivers/i3c/master/Kconfig b/drivers/i3c/master/Kconfig
> index 77da199c7413..a77d288d2464 100644
> --- a/drivers/i3c/master/Kconfig
> +++ b/drivers/i3c/master/Kconfig
> @@ -1,4 +1,20 @@
> # SPDX-License-Identifier: GPL-2.0-only
> +
> +config AMD_I3C_MASTER
> + tristate "AMD I3C Master driver"
> + depends on I3C
> + depends on HAS_IOMEM
> + help
> + Support for AMD I3C Master Controller.
> +
> + This driver allows communication with I3C devices using the AMD
> + I3C master, currently supporting Standard Data Rate (SDR) mode.
> + Features include Dynamic Address Assignment, private transfers,
> + and CCC transfers in both broadcast and direct modes.
> +
> + This driver can also be built as a module. If so, the module
> + will be called amd-i3c-master.
> +
> config CDNS_I3C_MASTER
> tristate "Cadence I3C master driver"
> depends on I3C
> diff --git a/drivers/i3c/master/Makefile b/drivers/i3c/master/Makefile
> index 3e97960160bc..c0167aa1f1b3 100644
> --- a/drivers/i3c/master/Makefile
> +++ b/drivers/i3c/master/Makefile
> @@ -1,4 +1,5 @@
> # SPDX-License-Identifier: GPL-2.0-only
> +obj-$(CONFIG_AMD_I3C_MASTER) += amd-i3c-master.o
> obj-$(CONFIG_CDNS_I3C_MASTER) += i3c-master-cdns.o
> obj-$(CONFIG_DW_I3C_MASTER) += dw-i3c-master.o
> obj-$(CONFIG_AST2600_I3C_MASTER) += ast2600-i3c-master.o
> diff --git a/drivers/i3c/master/amd-i3c-master.c b/drivers/i3c/master/amd-i3c-master.c
> new file mode 100644
> index 000000000000..f74febe4d17d
> --- /dev/null
> +++ b/drivers/i3c/master/amd-i3c-master.c
> @@ -0,0 +1,1009 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * I3C master driver for the AMD I3C controller.
> + *
> + * Copyright (C) 2025, Advanced Micro Devices, Inc.
> + */
> +
> +#include <linux/bitops.h>
> +#include <linux/clk.h>
> +#include <linux/err.h>
> +#include <linux/errno.h>
> +#include <linux/i3c/master.h>
> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/iopoll.h>
> +#include <linux/ioport.h>
> +#include <linux/kernel.h>
> +#include <linux/list.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +#include <linux/unaligned.h>
> +
> +#define XI3C_VERSION_OFFSET 0x00 /* Version Register */
> +#define XI3C_RESET_OFFSET 0x04 /* Soft Reset Register */
> +#define XI3C_CR_OFFSET 0x08 /* Control Register */
> +#define XI3C_ADDRESS_OFFSET 0x0C /* Target Address Register */
> +#define XI3C_SR_OFFSET 0x10 /* Status Register */
> +#define XI3C_CMD_FIFO_OFFSET 0x20 /* I3C Command FIFO Register */
> +#define XI3C_WR_FIFO_OFFSET 0x24 /* I3C Write Data FIFO Register */
> +#define XI3C_RD_FIFO_OFFSET 0x28 /* I3C Read Data FIFO Register */
> +#define XI3C_RESP_STATUS_FIFO_OFFSET 0x2C /* I3C Response status FIFO Register */
> +#define XI3C_FIFO_LVL_STATUS_OFFSET 0x30 /* I3C CMD & WR FIFO LVL Register */
> +#define XI3C_FIFO_LVL_STATUS_1_OFFSET 0x34 /* I3C RESP & RD FIFO LVL Register */
> +#define XI3C_SCL_HIGH_TIME_OFFSET 0x38 /* I3C SCL HIGH Register */
> +#define XI3C_SCL_LOW_TIME_OFFSET 0x3C /* I3C SCL LOW Register */
> +#define XI3C_SDA_HOLD_TIME_OFFSET 0x40 /* I3C SDA HOLD Register */
> +#define XI3C_TSU_START_OFFSET 0x48 /* I3C START SETUP Register */
> +#define XI3C_THD_START_OFFSET 0x4C /* I3C START HOLD Register */
> +#define XI3C_TSU_STOP_OFFSET 0x50 /* I3C STOP Setup Register */
> +#define XI3C_OD_SCL_HIGH_TIME_OFFSET 0x54 /* I3C OD SCL HIGH Register */
> +#define XI3C_OD_SCL_LOW_TIME_OFFSET 0x58 /* I3C OD SCL LOW Register */
> +#define XI3C_PID0_OFFSET 0x6C /* LSB 4 bytes of the PID */
> +#define XI3C_PID1_BCR_DCR 0x70 /* MSB 2 bytes of the PID, BCR and DCR */
> +
> +#define XI3C_CR_EN_MASK BIT(0) /* Core Enable */
> +#define XI3C_CR_RESUME_MASK BIT(2) /* Core Resume */
> +#define XI3C_SR_RESP_NOT_EMPTY_MASK BIT(4) /* Resp Fifo not empty status mask */
> +
> +#define XI3C_BCR_MASK GENMASK(23, 16)
> +#define XI3C_DCR_MASK GENMASK(31, 24)
> +#define XI3C_PID_MASK GENMASK(63, 16)
> +#define XI3C_SCL_HIGH_TIME_MASK GENMASK(17, 0)
> +#define XI3C_SCL_LOW_TIME_MASK GENMASK(17, 0)
> +#define XI3C_SDA_HOLD_TIME_MASK GENMASK(17, 0)
> +#define XI3C_TSU_START_MASK GENMASK(17, 0)
> +#define XI3C_THD_START_MASK GENMASK(17, 0)
> +#define XI3C_TSU_STOP_MASK GENMASK(17, 0)
> +#define XI3C_REV_NUM_MASK GENMASK(15, 8)
> +#define XI3C_PID1_MASK GENMASK(15, 0)
> +#define XI3C_WR_FIFO_LEVEL_MASK GENMASK(15, 0)
> +#define XI3C_CMD_LEN_MASK GENMASK(11, 0)
> +#define XI3C_RESP_CODE_MASK GENMASK(8, 5)
> +#define XI3C_ADDR_MASK GENMASK(6, 0)
> +#define XI3C_CMD_TYPE_MASK GENMASK(3, 0)
> +#define XI3C_CMD_TID_MASK GENMASK(3, 0)
> +#define XI3C_FIFOS_RST_MASK GENMASK(4, 1)
> +
> +#define XI3C_OD_TLOW_NS 500000
> +#define XI3C_OD_THIGH_NS 41000
> +#define XI3C_I2C_TCASMIN_NS 600000
> +#define XI3C_TCASMIN_NS 260000
> +#define XI3C_MAXDATA_LENGTH 4095
> +#define XI3C_MAX_DEVS 32
> +#define XI3C_DAA_SLAVEINFO_READ_BYTECOUNT 8
> +
> +#define XI3C_I2C_MODE 0
> +#define XI3C_I2C_TID 0
> +#define XI3C_SDR_MODE 1
> +#define XI3C_SDR_TID 1
> +
> +#define XI3C_WORD_LEN 4
> +
> +/* timeout waiting for the controller finish transfers */
> +#define XI3C_XFER_TIMEOUT (msecs_to_jiffies(10000))
> +#define XI3C_XFER_TIMEOUT_MS 10000

Only define one TIMEOUT should be enough

s/XI3C_XFER_TIMEOUT/(msecs_to_jiffies(XI3C_XFER_TIMEOUT_MS))

> +
> +#define xi3c_getrevisionnumber(master) \
> + ((u8)(FIELD_GET(XI3C_REV_NUM_MASK, \
> + readl((master)->membase + XI3C_VERSION_OFFSET))))
> +
> +#define xi3c_wrfifolevel(master) \
> + ((u16)(readl((master)->membase + XI3C_FIFO_LVL_STATUS_OFFSET) & \
> + XI3C_WR_FIFO_LEVEL_MASK))
> +
> +#define xi3c_rdfifolevel(master) \
> + ((u16)(readl((master)->membase + XI3C_FIFO_LVL_STATUS_1_OFFSET) & \
> + XI3C_WR_FIFO_LEVEL_MASK))
> +
> +#define xi3c_is_resp_available(master) \
> + ((u8)(FIELD_GET(XI3C_SR_RESP_NOT_EMPTY_MASK, \
> + readl((master)->membase + XI3C_SR_OFFSET))))

Are you sure need type force convert at above macro?

> +
> +struct xi3c_cmd {
> + void *tx_buf;
> + void *rx_buf;
> + u16 tx_len;
> + u16 rx_len;
> + u8 addr;
> + u8 type;
> + u8 tid;
> + bool rnw;
> + bool is_daa;
> + bool continued;
> +};
> +
> +struct xi3c_xfer {
> + struct list_head node;
> + struct completion comp;
> + int ret;
> + unsigned int ncmds;
> + struct xi3c_cmd cmds[] __counted_by(ncmds);
> +};
> +
> +/**
> + * struct xi3c_master - I3C Master structure
> + * @base: I3C master controller
> + * @dev: Pointer to device structure
> + * @xferqueue: Transfer queue structure
> + * @xferqueue.list: List member
> + * @xferqueue.cur: Current ongoing transfer
> + * @xferqueue.lock: Queue lock
> + * @membase: Memory base of the HW registers
> + * @pclk: Input clock
> + * @lock: Transfer lock
> + * @daa.addrs: Slave addresses array
> + * @daa.index: Slave device index
> + */
> +struct xi3c_master {
> + struct i3c_master_controller base;
> + struct device *dev;
> + struct {
> + struct list_head list;
> + struct xi3c_xfer *cur;
> + /* Queue lock */
> + spinlock_t lock;
> + } xferqueue;
> + void __iomem *membase;
> + struct clk *pclk;
> + /* Transfer lock */
> + struct mutex lock;
> + struct {
> + u8 addrs[XI3C_MAX_DEVS];
> + u8 index;
> + } daa;
> +};
> +
> +static inline struct xi3c_master *
> +to_xi3c_master(struct i3c_master_controller *master)
> +{
> + return container_of(master, struct xi3c_master, base);
> +}
> +
> +static int xi3c_get_response(struct xi3c_master *master)
> +{
> + u32 resp_reg, response_data;
> + int ret;
> +
> + ret = readl_poll_timeout(master->membase + XI3C_SR_OFFSET,
> + resp_reg,
> + resp_reg & XI3C_SR_RESP_NOT_EMPTY_MASK,
> + 0, XI3C_XFER_TIMEOUT_MS);
> + if (ret) {
> + dev_err(master->dev, "AXI I3C response timeout\n");
> + return ret;
> + }
> +
> + response_data = readl(master->membase + XI3C_RESP_STATUS_FIFO_OFFSET);
> +
> + /* Return response code */
> + return FIELD_GET(XI3C_RESP_CODE_MASK, response_data);
> +}
> +
> +static void xi3c_master_wr_to_tx_fifo(struct xi3c_master *master,
> + struct xi3c_cmd *cmd)
> +{
> + u8 *tx_buf = (u8 *)cmd->tx_buf;
> + u32 data = 0;
> + u16 len;
> +
> + len = cmd->tx_len;
> + if (len > 0) {
> + len = (len >= XI3C_WORD_LEN) ? XI3C_WORD_LEN : len;
> + memcpy(&data, tx_buf, len);
> + tx_buf += len;
> + cmd->tx_len -= len;
> + }
> + cmd->tx_buf = tx_buf;
> +
> + /* Write the 32-bit value to the Tx FIFO */
> + iowrite32be(data, master->membase + XI3C_WR_FIFO_OFFSET);
> +}
> +
> +static void xi3c_master_rd_from_rx_fifo(struct xi3c_master *master,
> + struct xi3c_cmd *cmd)
> +{
> + u32 data;
> + u16 len;
> +
> + /* Read from Rx FIFO */
> + data = ioread32be(master->membase + XI3C_RD_FIFO_OFFSET);
> +
> + /* Data extraction to rx buffer */
> + len = cmd->rx_len;
> + if (len > 0) {
> + len = (len >= XI3C_WORD_LEN) ? XI3C_WORD_LEN : len;
> + memcpy((u8 *)cmd->rx_buf, &data, len);
> + cmd->rx_buf = (u8 *)cmd->rx_buf + len;
> + cmd->rx_len -= len;
> + }
> +}

Check i3c_writel_fifo() and i3c_readl_fifo(), which do the similar thing.

> +
> +static void xi3c_master_write_to_cmdfifo(struct xi3c_master *master,
> + struct xi3c_cmd *cmd, u16 len)
> +{
> + u32 transfer_cmd = 0;
> + u8 addr;
> +
> + addr = ((cmd->addr & XI3C_ADDR_MASK) << 1) | (cmd->rnw & BIT(0));
> +
> + transfer_cmd = cmd->type & XI3C_CMD_TYPE_MASK;
> + transfer_cmd |= (u32)(!cmd->continued) << 4;
> + transfer_cmd |= (u32)(addr) << 8;
> + transfer_cmd |= (u32)(cmd->tid & XI3C_CMD_TID_MASK) << 28;

Can you use GEN_MASK to avoid hardcode 4, 8, 28

> +
> + /*
> + * For dynamic addressing, an additional 1-byte length must be added
> + * to the command FIFO to account for the address present in the TX FIFO
> + */
> + if (cmd->is_daa) {
> + xi3c_master_wr_to_tx_fifo(master, cmd);
> +
> + len++;
> + master->daa.index++;
> + cmd->is_daa = false;
> + }
> +
> + transfer_cmd |= (u32)(len & XI3C_CMD_LEN_MASK) << 16;

And 16 here.

> + writel(transfer_cmd, master->membase + XI3C_CMD_FIFO_OFFSET);
> +}
> +
> +static inline void xi3c_master_enable(struct xi3c_master *master)
> +{
> + writel(readl(master->membase + XI3C_CR_OFFSET) | XI3C_CR_EN_MASK,
> + master->membase + XI3C_CR_OFFSET);
> +}
> +
> +static inline void xi3c_master_disable(struct xi3c_master *master)
> +{
> + writel(readl(master->membase + XI3C_CR_OFFSET) & (~XI3C_CR_EN_MASK),
> + master->membase + XI3C_CR_OFFSET);
> +}
> +
> +static inline void xi3c_master_resume(struct xi3c_master *master)
> +{
> + writel(readl(master->membase + XI3C_CR_OFFSET) | XI3C_CR_RESUME_MASK,
> + master->membase + XI3C_CR_OFFSET);
> +}
> +
> +static void xi3c_master_reset_fifos(struct xi3c_master *master)
> +{
> + u32 data;
> +
> + /* Reset fifos */
> + data = readl(master->membase + XI3C_RESET_OFFSET);

you mix use readl and ioread32, can you keep consistence?

> + data |= XI3C_FIFOS_RST_MASK;
> + writel(data, master->membase + XI3C_RESET_OFFSET);
> + udelay(10);

udelay() may not include MMIO operation, it may delay less than 10us.
suggest readl() before udelay() to make sure value reach XI3C_RESET_OFFSET.

> + data &= ~XI3C_FIFOS_RST_MASK;
> + writel(data, master->membase + XI3C_RESET_OFFSET);
> + udelay(10);
> +}
> +
> +static inline void xi3c_master_init(struct xi3c_master *master)
> +{
> + /* Reset fifos */
> + xi3c_master_reset_fifos(master);
> +
> + /* Enable controller */
> + xi3c_master_enable(master);
> +}
> +
> +static inline void xi3c_master_reinit(struct xi3c_master *master)
> +{
> + /* Reset fifos */
> + xi3c_master_reset_fifos(master);
> +
> + /* Resume controller */
> + xi3c_master_resume(master);
> +}
> +
> +static struct xi3c_xfer *
> +xi3c_master_alloc_xfer(struct xi3c_master *master, unsigned int ncmds)
> +{
> + struct xi3c_xfer *xfer;
> +
> + xfer = kzalloc(struct_size(xfer, cmds, ncmds), GFP_KERNEL);
> + if (!xfer)
> + return NULL;
> +
> + INIT_LIST_HEAD(&xfer->node);
> + xfer->ncmds = ncmds;
> + xfer->ret = -ETIMEDOUT;
> +
> + return xfer;
> +}
> +
> +static inline void xi3c_master_free_xfer(struct xi3c_xfer *xfer)
> +{
> + kfree(xfer);
> +}

why not direct call kfree()?

> +
> +static int xi3c_master_read(struct xi3c_master *master, struct xi3c_cmd *cmd)
> +{
> + unsigned long timeout;
> + u16 rx_data_available;
> + u16 data_index;
> +
> + if (!cmd->rx_buf || cmd->rx_len > XI3C_MAXDATA_LENGTH)
> + return -EINVAL;
> +
> + /* Fill command fifo */
> + xi3c_master_write_to_cmdfifo(master, cmd, cmd->rx_len);
> +
> + timeout = jiffies + XI3C_XFER_TIMEOUT;
> + /* Read data from rx fifo */
> + while (cmd->rx_len > 0 && !xi3c_is_resp_available(master)) {
> + if (time_after(jiffies, timeout)) {
> + dev_err(master->dev, "XI3C read timeout\n");
> + return -EIO;
> + }
> +
> + rx_data_available = xi3c_rdfifolevel(master);
> + for (data_index = 0;
> + data_index < rx_data_available && cmd->rx_len > 0;
> + data_index++)
> + xi3c_master_rd_from_rx_fifo(master, cmd);
> + }
> +
> + /* Read remaining data */
> + rx_data_available = xi3c_rdfifolevel(master);
> + for (data_index = 0;
> + data_index < rx_data_available && cmd->rx_len > 0;
> + data_index++)
> + xi3c_master_rd_from_rx_fifo(master, cmd);
> + return 0;
> +}
> +
> +static int xi3c_master_write(struct xi3c_master *master, struct xi3c_cmd *cmd)
> +{
> + unsigned long timeout;
> + u16 wrfifo_space;
> + u16 space_index;
> + u16 len;
> +
> + len = cmd->tx_len;
> + if (!cmd->tx_buf || cmd->tx_len > XI3C_MAXDATA_LENGTH)
> + return -EINVAL;
> +
> + /* Fill Tx fifo */
> + wrfifo_space = xi3c_wrfifolevel(master);
> + for (space_index = 0; space_index < wrfifo_space && cmd->tx_len > 0;
> + space_index++)
> + xi3c_master_wr_to_tx_fifo(master, cmd);

Does existed helper function i3c_writel_fifo() handle this?

> +
> + /* Write to command fifo */
> + xi3c_master_write_to_cmdfifo(master, cmd, len);
> +
> + timeout = jiffies + XI3C_XFER_TIMEOUT;
> + /* Fill if any remaining data to tx fifo */
> + while (cmd->tx_len > 0 && !xi3c_is_resp_available(master)) {
> + if (time_after(jiffies, timeout)) {
> + dev_err(master->dev, "XI3C write timeout\n");
> + return -EIO;
> + }
> +
> + wrfifo_space = xi3c_wrfifolevel(master);
> + for (space_index = 0; space_index < wrfifo_space && cmd->tx_len > 0;
> + space_index++)
> + xi3c_master_wr_to_tx_fifo(master, cmd);
> + }
> + return 0;
> +}
> +
> +static int xi3c_master_xfer(struct xi3c_master *master, struct xi3c_cmd *cmd)
> +{
> + int ret;
> +
> + if (cmd->rnw)
> + ret = xi3c_master_read(master, cmd);
> + else
> + ret = xi3c_master_write(master, cmd);
> +
> + if (ret < 0)
> + goto err_xfer_out;
> +
> + ret = xi3c_get_response(master);
> + if (ret)
> + goto err_xfer_out;
> +
> + return 0;
> +
> +err_xfer_out:
> + xi3c_master_reinit(master);
> + return ret;
> +}
> +
> +static void xi3c_master_dequeue_xfer_locked(struct xi3c_master *master,
> + struct xi3c_xfer *xfer)
> +{
> + if (master->xferqueue.cur == xfer)
> + master->xferqueue.cur = NULL;
> + else
> + list_del_init(&xfer->node);
> +}
> +
> +static void xi3c_master_dequeue_xfer(struct xi3c_master *master,
> + struct xi3c_xfer *xfer)
> +{
> + guard(spinlock_irqsave)(&master->xferqueue.lock);

Add empty line here.

> + xi3c_master_dequeue_xfer_locked(master, xfer);
> +}
> +
> +static void xi3c_master_start_xfer_locked(struct xi3c_master *master)
> +{
> + struct xi3c_xfer *xfer = master->xferqueue.cur;
> + int ret = 0, i;
> +
> + if (!xfer)
> + return;
> +
> + for (i = 0; i < xfer->ncmds; i++) {
> + struct xi3c_cmd *cmd = &xfer->cmds[i];
> +
> + ret = xi3c_master_xfer(master, cmd);
> + if (ret)
> + break;
> + }
> +
> + xfer->ret = ret;
> + complete(&xfer->comp);
> +
> + xfer = list_first_entry_or_null(&master->xferqueue.list,
> + struct xi3c_xfer,
> + node);
> + if (xfer)
> + list_del_init(&xfer->node);
> +
> + master->xferqueue.cur = xfer;
> + xi3c_master_start_xfer_locked(master);
> +}
> +
> +static inline void xi3c_master_enqueue_xfer(struct xi3c_master *master,
> + struct xi3c_xfer *xfer)
> +{
> + init_completion(&xfer->comp);
> + guard(spinlock_irqsave)(&master->xferqueue.lock);
> + if (master->xferqueue.cur) {
> + list_add_tail(&xfer->node, &master->xferqueue.list);
> + } else {
> + master->xferqueue.cur = xfer;
> + xi3c_master_start_xfer_locked(master);
> + }
> +}
> +
> +static inline int xi3c_master_common_xfer(struct xi3c_master *master,
> + struct xi3c_xfer *xfer)
> +{
> + int ret, timeout;
> +
> + guard(mutex)(&master->lock);
> + xi3c_master_enqueue_xfer(master, xfer);
> + timeout = wait_for_completion_timeout(&xfer->comp,
> + msecs_to_jiffies(XI3C_XFER_TIMEOUT_MS));
> + if (!timeout)
> + ret = -ETIMEDOUT;
> + else
> + ret = xfer->ret;
> +
> + if (ret)
> + xi3c_master_dequeue_xfer(master, xfer);
> +
> + return ret;
> +}
> +
> +static int xi3c_master_do_daa(struct i3c_master_controller *m)
> +{
> + struct xi3c_master *master = to_xi3c_master(m);
> + struct xi3c_cmd *daa_cmd;
> + struct xi3c_xfer *xfer;
> + u8 pid_bufs[XI3C_MAX_DEVS][8];
> + u8 data, last_addr = 0;
> + int addr, ret, i;
> + u8 *pid_buf;
> +
> + u64 *pid_bcr_dcr __free(kfree) = kcalloc(XI3C_MAX_DEVS, sizeof(u64),
> + GFP_KERNEL);
> + if (!pid_bcr_dcr)
> + return -ENOMEM;
> +
> + xfer = xi3c_master_alloc_xfer(master, 1);
> + if (!xfer) {
> + ret = -ENOMEM;
> + goto err_daa_mem;
> + }
> +
> + for (i = 0; i < XI3C_MAX_DEVS; i++) {
> + addr = i3c_master_get_free_addr(m, last_addr + 1);
> + if (addr < 0) {
> + ret = -ENOSPC;
> + goto err_daa;
> + }
> + master->daa.addrs[i] = (u8)addr;
> + last_addr = (u8)addr;
> + }
> +
> + /* Fill ENTDAA CCC */
> + data = I3C_CCC_ENTDAA;
> + daa_cmd = &xfer->cmds[0];
> + daa_cmd->addr = I3C_BROADCAST_ADDR;
> + daa_cmd->rnw = 0;
> + daa_cmd->tx_buf = &data;
> + daa_cmd->tx_len = 1;
> + daa_cmd->type = XI3C_SDR_MODE;
> + daa_cmd->tid = XI3C_SDR_TID;
> + daa_cmd->continued = true;
> +
> + ret = xi3c_master_common_xfer(master, xfer);
> + /* DAA always finishes with CE2_ERROR or NACK_RESP */
> + if (ret && ret != I3C_ERROR_M2) {
> + goto err_daa;
> + } else {
> + if (ret && ret == I3C_ERROR_M2) {
> + ret = 0;
> + goto err_daa;
> + }
> + }
> +
> + master->daa.index = 0;
> +
> + while (true) {
> + struct xi3c_cmd *cmd = &xfer->cmds[0];
> +
> + pid_buf = pid_bufs[master->daa.index];
> + addr = (master->daa.addrs[master->daa.index] << 1) |
> + (!parity8(master->daa.addrs[master->daa.index]));
> +
> + cmd->tx_buf = (u8 *)&addr;
> + cmd->tx_len = 1;
> + cmd->addr = I3C_BROADCAST_ADDR;
> + cmd->rnw = 1;
> + cmd->rx_buf = pid_buf;
> + cmd->rx_len = XI3C_DAA_SLAVEINFO_READ_BYTECOUNT;
> + cmd->is_daa = true;
> + cmd->type = XI3C_SDR_MODE;
> + cmd->tid = XI3C_SDR_TID;
> + cmd->continued = true;
> +
> + ret = xi3c_master_common_xfer(master, xfer);
> +
> + /* DAA always finishes with CE2_ERROR or NACK_RESP */
> + if (ret && ret != I3C_ERROR_M2) {
> + goto err_daa;
> + } else {
> + if (ret && ret == I3C_ERROR_M2) {
> + xi3c_master_resume(master);
> + master->daa.index--;
> + ret = 0;
> + break;
> + }
> + }
> + }
> +
> + xi3c_master_free_xfer(xfer);
> +
> + for (i = 0; i < master->daa.index; i++) {
> + ret = i3c_master_add_i3c_dev_locked(m, master->daa.addrs[i]);
> + if (ret)
> + goto err_daa_mem;

see comments in svc-master-i3c.c

/*
* Register all devices who participated to the core
*
* If two devices (A and B) are detected in DAA and address 0xa is assigned to
* device A and 0xb to device B, a failure in i3c_master_add_i3c_dev_locked()
* for device A (addr: 0xa) could prevent device B (addr: 0xb) from being
* registered on the bus. The I3C stack might still consider 0xb a free
* address. If a subsequent Hotjoin occurs, 0xb might be assigned to Device A,
* causing both devices A and B to use the same address 0xb, violating the I3C
* specification.
*
* The return value for i3c_master_add_i3c_dev_locked() should not be checked
* because subsequent steps will scan the entire I3C bus, independent of
* whether i3c_master_add_i3c_dev_locked() returns success.
*
* If device A registration fails, there is still a chance to register device
* B. i3c_master_add_i3c_dev_locked() can reset DAA if a failure occurs while
* retrieving device information.
*/

I think it also fits your case.

> +
> + pid_bcr_dcr[i] = FIELD_GET(XI3C_PID_MASK,
> + get_unaligned_be64(pid_bufs[i]));
> + dev_info(master->dev, "Client %d: PID: 0x%llx\n", i, pid_bcr_dcr[i]);
> + }
> +
> + return 0;
> +
> +err_daa:
> + xi3c_master_free_xfer(xfer);
> +err_daa_mem:
> + xi3c_master_reinit(master);
> + return ret;
> +}
> +
> +static bool
> +xi3c_master_supports_ccc_cmd(struct i3c_master_controller *master,
> + const struct i3c_ccc_cmd *cmd)
> +{
> + if (cmd->ndests > 1)
> + return false;
> +
> + switch (cmd->id) {
> + case I3C_CCC_ENEC(true):
> + case I3C_CCC_ENEC(false):
> + case I3C_CCC_DISEC(true):
> + case I3C_CCC_DISEC(false):
> + case I3C_CCC_ENTAS(0, true):
> + case I3C_CCC_ENTAS(0, false):
> + case I3C_CCC_RSTDAA(true):
> + case I3C_CCC_RSTDAA(false):
> + case I3C_CCC_ENTDAA:
> + case I3C_CCC_SETMWL(true):
> + case I3C_CCC_SETMWL(false):
> + case I3C_CCC_SETMRL(true):
> + case I3C_CCC_SETMRL(false):
> + case I3C_CCC_ENTHDR(0):
> + case I3C_CCC_SETDASA:
> + case I3C_CCC_SETNEWDA:
> + case I3C_CCC_GETMWL:
> + case I3C_CCC_GETMRL:
> + case I3C_CCC_GETPID:
> + case I3C_CCC_GETBCR:
> + case I3C_CCC_GETDCR:
> + case I3C_CCC_GETSTATUS:
> + case I3C_CCC_GETMXDS:
> + return true;
> + default:
> + return false;
> + }
> +}
> +
> +static int xi3c_master_send_bdcast_ccc_cmd(struct xi3c_master *master,
> + struct i3c_ccc_cmd *ccc)
> +{
> + u16 xfer_len = ccc->dests[0].payload.len + 1;
> + struct xi3c_xfer *xfer;
> + struct xi3c_cmd *cmd;
> + int ret;
> +
> + xfer = xi3c_master_alloc_xfer(master, 1);
> + if (!xfer)
> + return -ENOMEM;
> +
> + u8 *buf __free(kfree) = kmalloc(xfer_len, GFP_KERNEL);
> + if (!buf) {
> + xi3c_master_free_xfer(xfer);
> + return -ENOMEM;
> + }
> +
> + buf[0] = ccc->id;
> + memcpy(&buf[1], ccc->dests[0].payload.data, ccc->dests[0].payload.len);
> +
> + cmd = &xfer->cmds[0];
> + cmd->addr = ccc->dests[0].addr;
> + cmd->rnw = ccc->rnw;
> + cmd->tx_buf = buf;
> + cmd->tx_len = xfer_len;
> + cmd->type = XI3C_SDR_MODE;
> + cmd->tid = XI3C_SDR_TID;
> + cmd->continued = false;
> +
> + ret = xi3c_master_common_xfer(master, xfer);
> + xi3c_master_free_xfer(xfer);
> +
> + return ret;
> +}
> +
> +static int xi3c_master_send_direct_ccc_cmd(struct xi3c_master *master,
> + struct i3c_ccc_cmd *ccc)
> +{
> + struct xi3c_xfer *xfer;
> + struct xi3c_cmd *cmd;
> + int ret;
> +
> + xfer = xi3c_master_alloc_xfer(master, 2);
> + if (!xfer)
> + return -ENOMEM;
> +
> + /* Broadcasted message */
> + cmd = &xfer->cmds[0];
> + cmd->addr = I3C_BROADCAST_ADDR;
> + cmd->rnw = 0;
> + cmd->tx_buf = &ccc->id;
> + cmd->tx_len = 1;
> + cmd->type = XI3C_SDR_MODE;
> + cmd->tid = XI3C_SDR_TID;
> + cmd->continued = true;
> +
> + /* Directed message */
> + cmd = &xfer->cmds[1];
> + cmd->addr = ccc->dests[0].addr;
> + cmd->rnw = ccc->rnw;
> + if (cmd->rnw) {
> + cmd->rx_buf = ccc->dests[0].payload.data;
> + cmd->rx_len = ccc->dests[0].payload.len;
> + } else {
> + cmd->tx_buf = ccc->dests[0].payload.data;
> + cmd->tx_len = ccc->dests[0].payload.len;
> + }
> + cmd->type = XI3C_SDR_MODE;
> + cmd->tid = XI3C_SDR_TID;
> + cmd->continued = false;
> +
> + ret = xi3c_master_common_xfer(master, xfer);
> + xi3c_master_free_xfer(xfer);
> + return ret;
> +}
> +
> +static int xi3c_master_send_ccc_cmd(struct i3c_master_controller *m,
> + struct i3c_ccc_cmd *cmd)
> +{
> + struct xi3c_master *master = to_xi3c_master(m);
> + bool broadcast = cmd->id < 0x80;
> +
> + if (broadcast)
> + return xi3c_master_send_bdcast_ccc_cmd(master, cmd);
> +
> + return xi3c_master_send_direct_ccc_cmd(master, cmd);
> +}
> +
> +static int xi3c_master_priv_xfers(struct i3c_dev_desc *dev,
> + struct i3c_priv_xfer *xfers,
> + int nxfers)
> +{
> + struct i3c_master_controller *m = i3c_dev_get_master(dev);
> + struct xi3c_master *master = to_xi3c_master(m);
> + struct xi3c_xfer *xfer;
> + int i, ret;
> +
> + if (!nxfers)
> + return 0;
> +
> + xfer = xi3c_master_alloc_xfer(master, nxfers);
> + if (!xfer)
> + return -ENOMEM;
> +
> + for (i = 0; i < nxfers; i++) {
> + struct xi3c_cmd *cmd = &xfer->cmds[i];
> +
> + cmd->addr = dev->info.dyn_addr;
> + cmd->rnw = xfers[i].rnw;
> +
> + if (cmd->rnw) {
> + cmd->rx_buf = xfers[i].data.in;
> + cmd->rx_len = xfers[i].len;
> + } else {
> + cmd->tx_buf = (void *)xfers[i].data.out;
> + cmd->tx_len = xfers[i].len;
> + }
> +
> + cmd->type = XI3C_SDR_MODE;
> + cmd->tid = XI3C_SDR_TID;
> + cmd->continued = (i + 1) < nxfers;
> + }
> +
> + ret = xi3c_master_common_xfer(master, xfer);
> + xi3c_master_free_xfer(xfer);
> + return ret;
> +}
> +
> +static int xi3c_master_i2c_xfers(struct i2c_dev_desc *dev,
> + struct i2c_msg *xfers,
> + int nxfers)
> +{
> + struct i3c_master_controller *m = i2c_dev_get_master(dev);
> + struct xi3c_master *master = to_xi3c_master(m);
> + struct xi3c_xfer *xfer;
> + int i, ret;
> +
> + if (!nxfers)
> + return 0;
> +
> + xfer = xi3c_master_alloc_xfer(master, nxfers);
> + if (!xfer)
> + return -ENOMEM;
> +
> + for (i = 0; i < nxfers; i++) {
> + struct xi3c_cmd *cmd = &xfer->cmds[i];
> +
> + cmd->addr = xfers[i].addr & XI3C_ADDR_MASK;
> + cmd->rnw = xfers[i].flags & I2C_M_RD;
> +
> + if (cmd->rnw) {
> + cmd->rx_buf = xfers[i].buf;
> + cmd->rx_len = xfers[i].len;
> + } else {
> + cmd->tx_buf = (void *)xfers[i].buf;
> + cmd->tx_len = xfers[i].len;
> + }
> +
> + cmd->type = XI3C_I2C_MODE;
> + cmd->tid = XI3C_I2C_TID;
> + cmd->continued = (i + 1) < nxfers;
> + }
> +
> + ret = xi3c_master_common_xfer(master, xfer);
> + xi3c_master_free_xfer(xfer);
> + return ret;
> +}
> +
> +static int xi3c_clk_cfg(struct xi3c_master *master, unsigned long sclhz, u8 mode)
> +{
> + unsigned long core_rate, core_periodns;
> + u32 thigh, tlow, thold, odthigh, odtlow, tcasmin, tsustart, tsustop, thdstart;
> +
> + core_rate = clk_get_rate(master->pclk);
> + if (!core_rate)
> + return -EINVAL;
> +
> + core_periodns = DIV_ROUND_UP(1000000000, core_rate);
> +
> + thigh = DIV_ROUND_UP(core_rate, sclhz) >> 1;
> + tlow = thigh;
> +
> + /* Hold time : 40% of tlow time */
> + thold = (tlow * 4) / 10;
> +
> + /*
> + * For initial IP (revision number == 0), minimum data hold time is 5.
> + * For updated IP (revision number > 0), minimum data hold time is 6.
> + * Updated IP supports achieving high data rate with low reference
> + * frequency.
> + */
> + if (xi3c_getrevisionnumber(master) == 0)
> + thold = (thold < 5) ? 5 : thold;
> + else
> + thold = (thold < 6) ? 6 : thold;
> +
> + writel((thigh - 2) & XI3C_SCL_HIGH_TIME_MASK,
> + master->membase + XI3C_SCL_HIGH_TIME_OFFSET);
> + writel((tlow - 2) & XI3C_SCL_LOW_TIME_MASK,
> + master->membase + XI3C_SCL_LOW_TIME_OFFSET);
> + writel((thold - 2) & XI3C_SDA_HOLD_TIME_MASK,
> + master->membase + XI3C_SDA_HOLD_TIME_OFFSET);
> +
> + if (!mode) {
> + /* I2C */
> + writel((thigh - 2) & XI3C_SCL_HIGH_TIME_MASK,
> + master->membase + XI3C_OD_SCL_HIGH_TIME_OFFSET);
> + writel((tlow - 2) & XI3C_SCL_LOW_TIME_MASK,
> + master->membase + XI3C_OD_SCL_LOW_TIME_OFFSET);
> +
> + tcasmin = DIV_ROUND_UP(XI3C_I2C_TCASMIN_NS, core_periodns);
> + } else {
> + /* I3C */
> + odtlow = DIV_ROUND_UP(XI3C_OD_TLOW_NS, core_periodns);
> + odthigh = DIV_ROUND_UP(XI3C_OD_THIGH_NS, core_periodns);
> +
> + odtlow = (tlow < odtlow) ? odtlow : tlow;
> + odthigh = (thigh > odthigh) ? odthigh : thigh;
> +
> + writel((odthigh - 2) & XI3C_SCL_HIGH_TIME_MASK,
> + master->membase + XI3C_OD_SCL_HIGH_TIME_OFFSET);
> + writel((odtlow - 2) & XI3C_SCL_LOW_TIME_MASK,
> + master->membase + XI3C_OD_SCL_LOW_TIME_OFFSET);
> +
> + tcasmin = DIV_ROUND_UP(XI3C_TCASMIN_NS, core_periodns);
> + }
> +
> + thdstart = (thigh > tcasmin) ? thigh : tcasmin;
> + tsustart = (tlow > tcasmin) ? tlow : tcasmin;
> + tsustop = (tlow > tcasmin) ? tlow : tcasmin;
> +
> + writel((tsustart - 2) & XI3C_TSU_START_MASK,
> + master->membase + XI3C_TSU_START_OFFSET);
> + writel((thdstart - 2) & XI3C_THD_START_MASK,
> + master->membase + XI3C_THD_START_OFFSET);
> + writel((tsustop - 2) & XI3C_TSU_STOP_MASK,
> + master->membase + XI3C_TSU_STOP_OFFSET);
> +
> + return 0;
> +}
> +
> +static int xi3c_master_bus_init(struct i3c_master_controller *m)
> +{
> + struct xi3c_master *master = to_xi3c_master(m);
> + struct i3c_bus *bus = i3c_master_get_bus(m);
> + struct i3c_device_info info = { };
> + unsigned long sclhz;
> + u64 pid1_bcr_dcr;
> + u8 mode;
> + int ret;
> +
> + switch (bus->mode) {
> + case I3C_BUS_MODE_MIXED_FAST:
> + case I3C_BUS_MODE_MIXED_LIMITED:
> + mode = XI3C_I2C_MODE;
> + sclhz = bus->scl_rate.i2c;
> + break;
> + case I3C_BUS_MODE_PURE:
> + mode = XI3C_SDR_MODE;
> + sclhz = bus->scl_rate.i3c;
> + break;
> + default:
> + return -EINVAL;
> + }
> +
> + ret = xi3c_clk_cfg(master, sclhz, mode);
> + if (ret)
> + return ret;
> +
> + /* Get an address for the master. */
> + ret = i3c_master_get_free_addr(m, 0);
> + if (ret < 0)
> + return ret;
> +
> + info.dyn_addr = (u8)ret;
> +
> + /* Write the dynamic address value to the address register. */
> + writel(info.dyn_addr, master->membase + XI3C_ADDRESS_OFFSET);
> +
> + /* Read PID, BCR and DCR values, and assign to i3c device info. */
> + pid1_bcr_dcr = readl(master->membase + XI3C_PID1_BCR_DCR);
> + info.pid = ((FIELD_GET(XI3C_PID1_MASK, pid1_bcr_dcr) << 32) |
> + readl(master->membase + XI3C_PID0_OFFSET));
> + info.bcr = (u8)FIELD_GET(XI3C_BCR_MASK, pid1_bcr_dcr);
> + info.dcr = (u8)FIELD_GET(XI3C_DCR_MASK, pid1_bcr_dcr);
> +
> + ret = i3c_master_set_info(&master->base, &info);
> + if (ret)
> + return ret;
> +
> + xi3c_master_init(master);
> +
> + return ret;
> +}
> +
> +static void xi3c_master_bus_cleanup(struct i3c_master_controller *m)
> +{
> + struct xi3c_master *master = to_xi3c_master(m);
> +
> + xi3c_master_disable(master);
> +}
> +
> +static const struct i3c_master_controller_ops xi3c_master_ops = {
> + .bus_init = xi3c_master_bus_init,
> + .bus_cleanup = xi3c_master_bus_cleanup,
> + .do_daa = xi3c_master_do_daa,
> + .supports_ccc_cmd = xi3c_master_supports_ccc_cmd,
> + .send_ccc_cmd = xi3c_master_send_ccc_cmd,
> + .priv_xfers = xi3c_master_priv_xfers,
> + .i2c_xfers = xi3c_master_i2c_xfers,
> +};
> +
> +static int xi3c_master_probe(struct platform_device *pdev)
> +{
> + struct xi3c_master *master;
> +
> + master = devm_kzalloc(&pdev->dev, sizeof(*master), GFP_KERNEL);
> + if (!master)
> + return -ENOMEM;
> +
> + master->membase = devm_platform_ioremap_resource(pdev, 0);
> + if (IS_ERR(master->membase))
> + return PTR_ERR(master->membase);
> +
> + master->pclk = devm_clk_get_enabled(&pdev->dev, NULL);
> + if (IS_ERR(master->pclk))
> + return dev_err_probe(&pdev->dev, PTR_ERR(master->pclk),
> + "Failed to get and enable clock\n");
> +
> + master->dev = &pdev->dev;
> +
> + mutex_init(&master->lock);

devm_mutex_init()

Frank
> + spin_lock_init(&master->xferqueue.lock);
> + INIT_LIST_HEAD(&master->xferqueue.list);
> +
> + platform_set_drvdata(pdev, master);
> +
> + return i3c_master_register(&master->base, &pdev->dev,
> + &xi3c_master_ops, false);
> +}
> +
> +static void xi3c_master_remove(struct platform_device *pdev)
> +{
> + struct xi3c_master *master = platform_get_drvdata(pdev);
> +
> + i3c_master_unregister(&master->base);
> +}
> +
> +static const struct of_device_id xi3c_master_of_ids[] = {
> + { .compatible = "xlnx,axi-i3c-1.0" },
> + { },
> +};
> +
> +static struct platform_driver xi3c_master_driver = {
> + .probe = xi3c_master_probe,
> + .remove = xi3c_master_remove,
> + .driver = {
> + .name = "axi-i3c-master",
> + .of_match_table = xi3c_master_of_ids,
> + },
> +};
> +module_platform_driver(xi3c_master_driver);
> +
> +MODULE_AUTHOR("Manikanta Guntupalli <manikanta.guntupalli@amd.com>");
> +MODULE_DESCRIPTION("AXI I3C master driver");
> +MODULE_LICENSE("GPL");
> --
> 2.34.1