hw/misc: Add NPCM7XX MFT Module

This patch implements Multi Function Timer (MFT) module for NPCM7XX.
This module is mainly used to configure PWM fans. It has just enough
functionality to make the PWM fan kernel module work.

The module takes two input, the max_rpm of a fan (modifiable via QMP)
and duty cycle (a GPIO from the PWM module.) The actual measured RPM
is equal to max_rpm * duty_cycle / NPCM7XX_PWM_MAX_DUTY. The RPM is
measured as a counter compared to a prescaled input clock. The kernel
driver reads this counter and report to user space.

Refs:
https://github.com/torvalds/linux/blob/master/drivers/hwmon/npcm750-pwm-fan.c

Reviewed-by: Doug Evans <dje@google.com>
Reviewed-by: Tyrone Ting <kfting@nuvoton.com>
Signed-off-by: Hao Wu <wuhaotsh@google.com>
Message-id: 20210311180855.149764-3-wuhaotsh@google.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 70 insertions, 0 deletions

diff --git a/include/hw/misc/npcm7xx_mft.h b/include/hw/misc/npcm7xx_mft.h
new file mode 100644
index 0000000000..36785e3ba8
--- /dev/null
+++ b/include/hw/misc/npcm7xx_mft.h
@@ -0,0 +1,70 @@
+/*
+ * Nuvoton NPCM7xx MFT Module
+ *
+ * Copyright 2021 Google LLC
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * for more details.
+ */
+#ifndef NPCM7XX_MFT_H
+#define NPCM7XX_MFT_H
+
+#include "exec/memory.h"
+#include "hw/clock.h"
+#include "hw/irq.h"
+#include "hw/sysbus.h"
+#include "qom/object.h"
+
+/* Max Fan input number. */
+#define NPCM7XX_MFT_MAX_FAN_INPUT 19
+
+/*
+ * Number of registers in one MFT module. Don't change this without increasing
+ * the version_id in vmstate.
+ */
+#define NPCM7XX_MFT_NR_REGS (0x20 / sizeof(uint16_t))
+
+/*
+ * The MFT can take up to 4 inputs: A0, B0, A1, B1. It can measure one A and one
+ * B simultaneously. NPCM7XX_MFT_INASEL and NPCM7XX_MFT_INBSEL are used to
+ * select which A or B input are used.
+ */
+#define NPCM7XX_MFT_FANIN_COUNT 4
+
+/**
+ * struct NPCM7xxMFTState - Multi Functional Tachometer device state.
+ * @parent: System bus device.
+ * @iomem: Memory region through which registers are accessed.
+ * @clock_in: The input clock for MFT from CLK module.
+ * @clock_{1,2}: The counter clocks for NPCM7XX_MFT_CNT{1,2}
+ * @irq: The IRQ for this MFT state.
+ * @regs: The MMIO registers.
+ * @max_rpm: The maximum rpm for fans. Order: A0, B0, A1, B1.
+ * @duty: The duty cycles for fans, relative to NPCM7XX_PWM_MAX_DUTY.
+ */
+typedef struct NPCM7xxMFTState {
+    SysBusDevice parent;
+
+    MemoryRegion iomem;
+
+    Clock       *clock_in;
+    Clock       *clock_1, *clock_2;
+    qemu_irq    irq;
+    uint16_t    regs[NPCM7XX_MFT_NR_REGS];
+
+    uint32_t    max_rpm[NPCM7XX_MFT_FANIN_COUNT];
+    uint32_t    duty[NPCM7XX_MFT_FANIN_COUNT];
+} NPCM7xxMFTState;
+
+#define TYPE_NPCM7XX_MFT "npcm7xx-mft"
+#define NPCM7XX_MFT(obj) \
+    OBJECT_CHECK(NPCM7xxMFTState, (obj), TYPE_NPCM7XX_MFT)
+
+#endif /* NPCM7XX_MFT_H */