Re: [PATCH v5 4/4] misc: tps6594-pfsm: Add driver for TI TPS6594 PFSM

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On 3/30/23 10:35, Greg KH wrote:
On Thu, Mar 30, 2023 at 10:20:06AM +0200, Julien Panis wrote:
This PFSM controls the operational modes of the PMIC:
- STANDBY and LP_STANDBY,
- ACTIVE state,
- MCU_ONLY state,
- RETENTION state, with or without DDR and/or GPIO retention.
Depending on the current operational mode, some voltage domains
remain energized while others can be off.

This PFSM is also used to trigger a firmware update, and provides
R/W access to device registers.
What userspace code uses these new ioctls?  Do you have a pointer to it
anywhere?

I will provide a user app in 'samples' directory in v6.


--- /dev/null
+++ b/include/uapi/linux/tps6594_pfsm.h
@@ -0,0 +1,45 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * Userspace ABI for TPS6594 PMIC Pre-configurable Finite State Machine
+ *
+ * Copyright (C) 2023 BayLibre Incorporated - https://www.baylibre.com/
+ */
+
+#ifndef __TPS6594_PFSM_H
+#define __TPS6594_PFSM_H
+
+#include <linux/const.h>
+#include <linux/ioctl.h>
+#include <linux/types.h>
+
+/* PFSM state definitions */
+enum pfsm_state {
+	PMIC_ACTIVE_STATE,
+	PMIC_MCU_ONLY_STATE,
+	PMIC_RETENTION_STATE
+};
+
+/**
+ * struct pmic_state - PMIC state identification
+ * @state:   PFSM destination state
+ * @options: options for destination state
+ */
+struct pmic_state {
+	enum pfsm_state state;
+	__u8 options;
+};
+
+/* Commands */
+#define	PMIC_BASE			'P'
+
+#define	PMIC_GOTO_STANDBY		_IO(PMIC_BASE, 0)
+#define	PMIC_GOTO_LP_STANDBY		_IO(PMIC_BASE, 1)
+#define	PMIC_UPDATE_PGM			_IO(PMIC_BASE, 2)
+#define	PMIC_SET_STATE			_IOW(PMIC_BASE, 3, struct pmic_state)
+
+/* Options for destination state */
+#define PMIC_GPIO_RETENTION		_BITUL(0)
+#define PMIC_DDR_RETENTION		_BITUL(1)
+#define PMIC_MCU_ONLY_STARTUP_DEST	_BITUL(2)
Please read Documentation/driver-api/ioctl.rst which says:

* Bitfields and enums generally work as one would expect them to,
   but some properties of them are implementation-defined, so it is
   better to avoid them completely in ioctl interfaces.

For a brand-new ioctl interface, you did both of these unrecommended
things.  Why set yourself for complexity when you do not need to?

I will fix that. Thank you for your feedback.

Julien




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