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misc: amd-sbi: Add support for register xfer

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- Provide user register access over IOCTL.
  Both register read and write are supported.
- APML interface does not provide a synchronization method. By defining,
  a register access path, we use APML modules and library for
  all APML transactions. Without having to use external tools such as
  i2c-tools, which may cause race conditions.

Reviewed-by: Naveen Krishna Chatradhi <naveenkrishna.chatradhi@amd.com>
Signed-off-by: Akshay Gupta <akshay.gupta@amd.com>
Link: https://lore.kernel.org/r/20250428063034.2145566-10-akshay.gupta@amd.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Akshay Gupta 2025-04-28 06:30:33 +00:00 • committed by Greg Kroah-Hartman
parent 69b1ba83d2
commit cf141287b7
2 changed files with 60 additions and 0 deletions
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29
drivers/misc/amd-sbi/rmi-core.c
View file

@ -350,6 +350,33 @@ exit_unlock:
return ret;
}
static int apml_rmi_reg_xfer(struct sbrmi_data *data,
struct apml_reg_xfer_msg __user *arg)
{
struct apml_reg_xfer_msg msg = { 0 };
unsigned int data_read;
int ret;
/* Copy the structure from user */
if (copy_from_user(&msg, arg, sizeof(struct apml_reg_xfer_msg)))
return -EFAULT;
mutex_lock(&data->lock);
if (msg.rflag) {
ret = regmap_read(data->regmap, msg.reg_addr, &data_read);
if (!ret)
msg.data_in_out = data_read;
} else {
ret = regmap_write(data->regmap, msg.reg_addr, msg.data_in_out);
}
mutex_unlock(&data->lock);
if (msg.rflag && !ret)
return copy_to_user(arg, &msg, sizeof(struct apml_reg_xfer_msg));
return ret;
}
static int apml_mailbox_xfer(struct sbrmi_data *data, struct apml_mbox_msg __user *arg)
{
struct apml_mbox_msg msg = { 0 };
@ -414,6 +441,8 @@ static long sbrmi_ioctl(struct file *fp, unsigned int cmd, unsigned long arg)
return apml_cpuid_xfer(data, argp);
case SBRMI_IOCTL_MCAMSR_CMD:
return apml_mcamsr_xfer(data, argp);
case SBRMI_IOCTL_REG_XFER_CMD:
return apml_rmi_reg_xfer(data, argp);
default:
return -ENOTTY;
}

31
include/uapi/misc/amd-apml.h
View file

@ -58,6 +58,21 @@ struct apml_mcamsr_msg {
__u32 pad;
};
struct apml_reg_xfer_msg {
/*
* RMI register address offset
*/
__u16 reg_addr;
/*
* Register data for read/write
*/
__u8 data_in_out;
/*
* Register read or write
*/
__u8 rflag;
};
/*
* AMD sideband interface base IOCTL
*/
@ -118,4 +133,20 @@ struct apml_mcamsr_msg {
*/
#define SBRMI_IOCTL_MCAMSR_CMD _IOWR(SB_BASE_IOCTL_NR, 2, struct apml_mcamsr_msg)
/**
* DOC: SBRMI_IOCTL_REG_XFER_CMD
*
* @Parameters
*
* @struct apml_reg_xfer_msg
* Pointer to the &struct apml_reg_xfer_msg that will contain the protocol
* information
*
* @Description
* IOCTL command for APML messages using generic _IOWR
* The IOCTL provides userspace access to AMD sideband register xfer protocol
* - Register xfer protocol to get/set hardware register for given offset
*/
#define SBRMI_IOCTL_REG_XFER_CMD _IOWR(SB_BASE_IOCTL_NR, 3, struct apml_reg_xfer_msg)
#endif /*_AMD_APML_H_*/