Re: [PATCH v3 2/2] mfd: max597x: Add support for MAX5970 and MAX5978

From: Naresh Solanki
Date: Tue Nov 01 2022 - 12:40:14 EST


Hi Christophe,

On 01-11-2022 02:49 am, Christophe JAILLET wrote:
Le 31/10/2022 à 21:41, Naresh Solanki a écrit :
From: Patrick Rudolph <patrick.rudolph@xxxxxxxxxxxxx>

Implement a regulator driver with IRQ support for fault management.
Written against documentation [1] and [2] and tested on real hardware.

Every channel has its own regulator supplies nammed 'vss1-supply' and
'vss2-supply'. The regulator supply is used to determine the output
voltage, as the smart switch provides no output regulation.
The driver requires the 'shunt-resistor-micro-ohms' property to be
present in Device Tree to properly calculate current related
values.

Datasheet links:
1: https://datasheets.maximintegrated.com/en/ds/MAX5970.pdf
2: https://datasheets.maximintegrated.com/en/ds/MAX5978.pdf

Signed-off-by: Patrick Rudolph <patrick.rudolph@xxxxxxxxxxxxx>
Signed-off-by: Marcello Sylvester Bauer <sylv@xxxxxxx>
Signed-off-by: Naresh Solanki <Naresh.Solanki@xxxxxxxxxxxxx>

Hi,
a few nits below.

---
  drivers/mfd/Kconfig         |  12 +++++
  drivers/mfd/Makefile        |   1 +
  drivers/mfd/max597x.c       |  87 ++++++++++++++++++++++++++++++
  include/linux/mfd/max597x.h | 102 ++++++++++++++++++++++++++++++++++++
  4 files changed, 202 insertions(+)
  create mode 100644 drivers/mfd/max597x.c
  create mode 100644 include/linux/mfd/max597x.h

diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index 8b93856de432..416fe7986b7b 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -253,6 +253,18 @@ config MFD_MADERA_SPI
        Support for the Cirrus Logic Madera platform audio SoC
        core functionality controlled via SPI.
+config MFD_MAX597X
+    tristate "Maxim 597x Power Switch and Monitor"
+    depends on I2C
+    depends on OF
+    select MFD_CORE
+    select REGMAP_I2C
+    help
+      This driver controls a Maxim 5970/5978 switch via I2C bus.
+      The MAX5970/5978 is a smart switch with no output regulation, but
+      fault protection and voltage and current monitoring capabilities.
+      Also it supports upto 4 indication LEDs.
+
  config MFD_CS47L15
      bool "Cirrus Logic CS47L15"
      select PINCTRL_CS47L15
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index 7ed3ef4a698c..819d711fa748 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -161,6 +161,7 @@ obj-$(CONFIG_MFD_DA9063)    += da9063.o
  obj-$(CONFIG_MFD_DA9150)    += da9150-core.o
  obj-$(CONFIG_MFD_MAX14577)    += max14577.o
+obj-$(CONFIG_MFD_MAX597X)    += max597x.o
  obj-$(CONFIG_MFD_MAX77620)    += max77620.o
  obj-$(CONFIG_MFD_MAX77650)    += max77650.o
  obj-$(CONFIG_MFD_MAX77686)    += max77686.o
diff --git a/drivers/mfd/max597x.c b/drivers/mfd/max597x.c
new file mode 100644
index 000000000000..68a4e7755f21
--- /dev/null
+++ b/drivers/mfd/max597x.c
@@ -0,0 +1,87 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Maxim MAX5970/MAX5978 MFD Driver
+ *
+ * Copyright (c) 2022 9elements GmbH
+ *
+ * Author: Patrick Rudolph <patrick.rudolph@xxxxxxxxxxxxx>
+ */
+
+#include <linux/i2c.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/max597x.h>
+#include <linux/regmap.h>
+
+static const struct regmap_config max597x_regmap_config = {
+    .reg_bits = 8,
+    .val_bits = 8,
+    .max_register = MAX_REGISTERS,
+};
+
+static const struct mfd_cell max597x_cells[] = {
+    { .name = "max597x-regulator", },
+    { .name = "max597x-iio", },
+    { .name = "max597x-led", },
+};
+
+static int max597x_probe(struct i2c_client *i2c, const struct i2c_device_id *id)
+{
+    struct max597x_data *ddata;
+    enum max597x_chip_type chip = id->driver_data;
+
+    ddata = devm_kzalloc(&i2c->dev, sizeof(*ddata),
+            GFP_KERNEL);

if (!ddata)
    return -ENOMEM;

Done
GFP_KERNEL should be aligned with the ( on the previous line.
Done

+
+    switch (chip) {
+    case MAX597x_TYPE_MAX5970:
+        ddata->num_switches = 2;
+        break;
+    case MAX597x_TYPE_MAX5978:
+        ddata->num_switches = 1;
+        break;
+    }

ddata->num_switches looks unused.
Is it needed? Maybe for future use?

Yes. Used by regulator & IIO driver.
Should MAX5970_NUM_SWITCHES and MAX5979_NUM_SWITCHES be used instead of hard coding 1 and 2?
Done

+
+    ddata->regmap = devm_regmap_init_i2c(i2c, &max597x_regmap_config);
+    if (IS_ERR(ddata->regmap)) {
+        dev_err(&i2c->dev, "Failed to initialise regmap");
+        return -EINVAL;
+    }
+
+    /* IRQ used by regulator cell */
+    ddata->irq = i2c->irq;
+    ddata->dev = &i2c->dev;
+    i2c_set_clientdata(i2c, ddata);
+
+    return devm_mfd_add_devices(ddata->dev, PLATFORM_DEVID_AUTO,
+                    max597x_cells, ARRAY_SIZE(max597x_cells),
+                    NULL, 0, NULL);
+}
+
+static const struct i2c_device_id max597x_table[] = {
+    { .name = "max5970", MAX597x_TYPE_MAX5970 },
+    { .name = "max5978", MAX597x_TYPE_MAX5978 },
+};
+
+MODULE_DEVICE_TABLE(i2c, max597x_table);
+
+static const struct of_device_id max597x_of_match[] = {
+    { .compatible = "maxim,max5970", .data = (void *)MAX597x_TYPE_MAX5970 },
+    { .compatible = "maxim,max5978", .data = (void *)MAX597x_TYPE_MAX5978 },
+};
+
+MODULE_DEVICE_TABLE(of, max597x_of_match);
+
+static struct i2c_driver max597x_driver = {
+    .id_table = max597x_table,
+    .driver = {
+        .name = "max597x",
+        .of_match_table = of_match_ptr(max597x_of_match),
+        },
+    .probe = max597x_probe,
+};
+
+module_i2c_driver(max597x_driver);
+
+MODULE_AUTHOR("Patrick Rudolph <patrick.rudolph@xxxxxxxxxxxxx>");
+MODULE_DESCRIPTION("MAX597X Power Switch and Monitor");
+MODULE_LICENSE("GPL v2");
diff --git a/include/linux/mfd/max597x.h b/include/linux/mfd/max597x.h
new file mode 100644
index 000000000000..ae7f38f0aee2
--- /dev/null
+++ b/include/linux/mfd/max597x.h
@@ -0,0 +1,102 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Maxim MAX5970/MAX5978 MFD Driver
+ *
+ * Copyright (c) 2022 9elements GmbH
+ *
+ * Author: Patrick Rudolph <patrick.rudolph@xxxxxxxxxxxxx>
+ */
+
+#ifndef MFD_MAX597X_H
+#define MFD_MAX597X_H
+
+#include <linux/device.h>
+#include <linux/regmap.h>
+
+#define MAX5970_NUM_SWITCHES 2
+#define MAX5978_NUM_SWITCHES 1
+#define MAX597X_NUM_LEDS     4

Unused?
Maybe the "4" below (or elsewhere) should be MAX597X_NUM_LEDS?
Yes. The chip has 4 indiaction leds. Used by led cell.

+
+enum max597x_chip_type {
+    MAX597x_TYPE_MAX5978 = 1,
+    MAX597x_TYPE_MAX5970,
+};
+
+#define MAX5970_REG_CURRENT_L(ch)        (0x01 + (ch) * 4)
+#define MAX5970_REG_CURRENT_H(ch)        (0x00 + (ch) * 4)
+#define MAX5970_REG_VOLTAGE_L(ch)        (0x03 + (ch) * 4)
+#define MAX5970_REG_VOLTAGE_H(ch)        (0x02 + (ch) * 4)
+#define MAX5970_REG_MON_RANGE            0x18
+#define  MAX5970_MON_MASK                0x3
+#define  MAX5970_MON(reg, ch) \
+                        (((reg) >> ((ch) * 2)) & MAX5970_MON_MASK)

Why a line break here?
Fixed.

+#define  MAX5970_MON_MAX_RANGE_UV        16000000
+
+#define MAX5970_REG_CH_UV_WARN_H(ch)    (0x1A + (ch) * 10)
+#define MAX5970_REG_CH_UV_WARN_L(ch)    (0x1B + (ch) * 10)
+#define MAX5970_REG_CH_UV_CRIT_H(ch)    (0x1C + (ch) * 10)
+#define MAX5970_REG_CH_UV_CRIT_L(ch)    (0x1D + (ch) * 10)
+#define MAX5970_REG_CH_OV_WARN_H(ch)    (0x1E + (ch) * 10)
+#define MAX5970_REG_CH_OV_WARN_L(ch)    (0x1F + (ch) * 10)
+#define MAX5970_REG_CH_OV_CRIT_H(ch)    (0x20 + (ch) * 10)
+#define MAX5970_REG_CH_OV_CRIT_L(ch)    (0x21 + (ch) * 10)
+
+#define  MAX5970_VAL2REG_H(x)            (((x) >> 2) & 0xFF)
+#define  MAX5970_VAL2REG_L(x)            ((x) & 0x3)
+
+#define MAX5970_REG_DAC_FAST(ch)        (0x2E + (ch))
+
+#define MAX5970_FAST2SLOW_RATIO            200
+
+#define MAX5970_REG_STATUS0                0x31
+#define  MAX5970_CB_IFAULTF(ch)            (1 << (ch))
+#define  MAX5970_CB_IFAULTS(ch)            (1 << ((ch) + 4))
+
+#define MAX5970_REG_STATUS1                0x32
+#define  STATUS1_PROT_MASK                0x3
+#define  STATUS1_PROT(reg) \
+    (((reg) >> 6) & STATUS1_PROT_MASK)
+#define  STATUS1_PROT_SHUTDOWN            0
+#define  STATUS1_PROT_CLEAR_PG            1
+#define  STATUS1_PROT_ALERT_ONLY        2
+
+#define MAX5970_REG_STATUS2                0x33
+#define  MAX5970_IRNG_MASK                0x3
+#define  MAX5970_IRNG(reg, ch)    \
+                        (((reg) >> ((ch) * 2)) & MAX5970_IRNG_MASK)
+
+#define MAX5970_REG_STATUS3                0x34
+#define  MAX5970_STATUS3_ALERT            BIT(4)
+#define  MAX5970_STATUS3_PG(ch)            BIT(ch)
+
+#define MAX5970_REG_FAULT0                0x35
+#define  UV_STATUS_WARN(ch)                BIT(ch)
+#define  UV_STATUS_CRIT(ch)                BIT(ch + 4)
+
+#define MAX5970_REG_FAULT1                0x36
+#define  OV_STATUS_WARN(ch)                BIT(ch)
+#define  OV_STATUS_CRIT(ch)                BIT(ch + 4)
+
+#define MAX5970_REG_FAULT2                0x37
+#define  OC_STATUS_WARN(ch)                BIT(ch)
+
+#define MAX5970_REG_CHXEN                0x3b
+#define  CHXEN(ch)                        (3 << (ch * 2))
+
+#define MAX5970_REG_LED_FLASH            0x43
+
+#define MAX_REGISTERS                    0x49
+#define ADC_MASK                        0x3FF
+
+struct max597x_data {
+    struct device *dev;
+    int irq;
+    int num_switches;
+    struct regmap *regmap;
+    /* Chip specific parameters needed by regulator & iio cells */
+    u32 irng[MAX5970_NUM_SWITCHES];
+    u32 mon_rng[MAX5970_NUM_SWITCHES];
+    u32 shunt_micro_ohms[MAX5970_NUM_SWITCHES];

mon_rng and shunt_micro_ohms look unused.
Are they needed? Maybe for future use?
Used by regulator & iio driver.

+};
+
+#endif                /* _MAX597X_H */

MFD_MAX597X_H

CJ

Thanks,
Naresh