[Public]

Hi,

-----Original Message-----
From: Guntupalli, Manikanta
Sent: Friday, September 12, 2025 4:56 PM
To: 'Frank Li' <Frank.li@nxp.com>
Cc: git (AMD-Xilinx) <redacted>; Simek, Michal <michal.simek@amd.com>;
'alexandre.belloni@bootlin.com' [off-list ref];
'robh@kernel.org' [off-list ref]; 'krzk+dt@kernel.org' [off-list ref];
'conor+dt@kernel.org' [off-list ref]; 'kees@kernel.org'
[off-list ref]; 'gustavoars@kernel.org' [off-list ref];
'jarkko.nikula@linux.intel.com' [off-list ref]; 'linux-
i3c@lists.infradead.org' [off-list ref];
'devicetree@vger.kernel.org' [off-list ref]; 'linux-
kernel@vger.kernel.org' [off-list ref]; 'linux-
hardening@vger.kernel.org' [off-list ref]; Pandey, Radhey
Shyam [off-list ref]; Goud, Srinivas
[off-list ref]; Datta, Shubhrajyoti [off-list ref];
'manion05gk@gmail.com' [off-list ref]
Subject: RE: [PATCH V6 2/2] i3c: master: Add AMD I3C bus controller driver

Hi,

quoted

-----Original Message-----
From: Guntupalli, Manikanta
Sent: Friday, September 12, 2025 11:25 AM
To: Frank Li <Frank.li@nxp.com>
Cc: git (AMD-Xilinx) <redacted>; Simek, Michal
[off-list ref]; alexandre.belloni@bootlin.com;
robh@kernel.org; krzk+dt@kernel.org;
conor+dt@kernel.org; kees@kernel.org; gustavoars@kernel.org;
jarkko.nikula@linux.intel.com; linux-i3c@lists.infradead.org;
devicetree@vger.kernel.org; linux-kernel@vger.kernel.org; linux-
hardening@vger.kernel.org; Pandey, Radhey Shyam
[off-list ref]; Goud, Srinivas [off-list ref];
Datta, Shubhrajyoti [off-list ref]; manion05gk@gmail.com
Subject: RE: [PATCH V6 2/2] i3c: master: Add AMD I3C bus controller
driver

Hi,

quoted

-----Original Message-----
From: Frank Li <Frank.li@nxp.com>
Sent: Thursday, September 11, 2025 9:15 PM
To: Guntupalli, Manikanta <redacted>
Cc: git (AMD-Xilinx) <redacted>; Simek, Michal
[off-list ref]; alexandre.belloni@bootlin.com;
robh@kernel.org; krzk+dt@kernel.org;
conor+dt@kernel.org; kees@kernel.org; gustavoars@kernel.org;
jarkko.nikula@linux.intel.com; linux-i3c@lists.infradead.org;
devicetree@vger.kernel.org; linux-kernel@vger.kernel.org; linux-
hardening@vger.kernel.org; Pandey, Radhey Shyam
[off-list ref]; Goud, Srinivas
[off-list ref]; Datta, Shubhrajyoti
[off-list ref]; manion05gk@gmail.com
Subject: Re: [PATCH V6 2/2] i3c: master: Add AMD I3C bus controller
driver

On Thu, Sep 11, 2025 at 06:07:59AM +0000, Guntupalli, Manikanta wrote:

quoted

[Public]

Hi,

quoted

-----Original Message-----
From: Frank Li <Frank.li@nxp.com>
Sent: Wednesday, September 10, 2025 10:25 PM
To: Guntupalli, Manikanta <redacted>
Cc: git (AMD-Xilinx) <redacted>; Simek, Michal
[off-list ref]; alexandre.belloni@bootlin.com;
robh@kernel.org; krzk+dt@kernel.org;
conor+dt@kernel.org; kees@kernel.org; gustavoars@kernel.org;
jarkko.nikula@linux.intel.com; linux-i3c@lists.infradead.org;
devicetree@vger.kernel.org; linux-kernel@vger.kernel.org; linux-
hardening@vger.kernel.org; Pandey, Radhey Shyam
[off-list ref]; Goud, Srinivas
[off-list ref]; Datta, Shubhrajyoti
[off-list ref]; manion05gk@gmail.com
Subject: Re: [PATCH V6 2/2] i3c: master: Add AMD I3C bus
controller driver

On Wed, Sep 10, 2025 at 04:59:54PM +0530, Manikanta Guntupalli wrote:

quoted

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
[off-list ref]
---
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.

Changes for V3:
Resolved merge conflicts.

Changes for V4:
Updated timeout macros.
Removed type casting for xi3c_is_resp_available() macro.
Used ioread32() and iowrite32() instead of readl() and
writel() to keep consistency.
Read XI3C_RESET_OFFSET reg before udelay().
Removed xi3c_master_free_xfer() and directly used kfree().
Skipped checking return value of i3c_master_add_i3c_dev_locked().
Used devm_mutex_init() instead of mutex_init().

Changes for V5:
Used GENMASK_ULL for PID mask as it's 64bit mask.

Changes for V6:
Removed typecast for xi3c_getrevisionnumber(),
xi3c_wrfifolevel(), and xi3c_rdfifolevel().
Replaced dynamic allocation with a static variable for pid_bcr_dcr.
Fixed sparse warning in do_daa by typecasting the address
parity value to u8.
Fixed sparse warning in xi3c_master_bus_init by typecasting
the pid value to u64 in info.pid calculation.
---
 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

1af81124bba3..ff603ce5e78d 100644

--- a/MAINTAINERS
+++ b/MAINTAINERS

@@ -11693,6 +11693,13 @@ 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 13df2944f2ec..4b884a678893
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 HAS_IOMEM

diff --git a/drivers/i3c/master/Makefile

b/drivers/i3c/master/Makefile index aac74f3e3851..109bd48cb159
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..cd9d85a0be80

--- /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.
+ */
+

...

quoted

+
+/* timeout waiting for the controller finish transfers */
+#define XI3C_XFER_TIMEOUT_MS                       10000
+#define XI3C_XFER_TIMEOUT

      (msecs_to_jiffies(XI3C_XFER_TIMEOUT_MS))

Do I missed your reply? I have not seen
https://lore.kernel.org/linux-i3c/aL7+Urm4NB9kwOwQ@lizhi-Precisi
on
-T
ower-5810/

If you need define two macro for it. Need unit
XI3C_XFER_TIMEOUT_JIFFIES to avoid confuse.

Sure, I'll update the macro name to XI3C_XFER_TIMEOUT_JIFFIES to
avoid

confusion.

quoted

quoted

quoted

+
+#define xi3c_getrevisionnumber(master)                                             \
+   (FIELD_GET(XI3C_REV_NUM_MASK,

      \

quoted

+              ioread32((master)->membase +
+ XI3C_VERSION_OFFSET)))
+

...

quoted

+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);
+ }

i3c_writel(readl)_fifo() did similar things, why not use it?

Did you miss my review comment or I missed your reply?

You have missed my earlier reply on this.
The helpers i3c_writel_fifo() and i3c_readl_fifo() rely on the
CPU's native endianness, whereas in this case the FIFO should
always be accessed in

big-endian format.

quoted

Hence, we cannot use the common helpers directly.

For reference, here's my previous reply:

https://lore.kernel.org/all/DM4PR12MB6109F6D5D032723C675472448C0FA@DM4

quoted

quoted

quoted

PR12MB6109.namprd12.prod.outlook.com/

Sorry, can you improve i3c_writel(readl)_fifo() to support endianness?
I think not only you have this kind problem in future.

Sure, will add support for endianness.

To add support for endianness, we could not find a big-endian counterpart to
writesl().
Please let me know if I missed any existing helper.

Endianness support for i3c_writel_fifo() and i3c_readl_fifo() would
require writesl_be() and readsl_be(), which are not currently available.
Implementing them introduces additional dependencies, so we suggest
handling endianness support in a follow-up patch series instead.
Please advise.

quoted

quoted

quoted

quoted

...

quoted

+
+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
+[off-list ref]"); MODULE_DESCRIPTION("AXI

I3C

quoted

quoted

quoted

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+master driver");

MODULE_LICENSE("GPL");

quoted

--
2.34.1

Thanks,
Manikanta.