Re: [PATCH 2/6] mfd: spacemit: add support for SpacemiT PMICs
From: Alex Elder
Date: Fri Jun 20 2025 - 10:11:10 EST
On 6/19/25 9:40 AM, Lee Jones wrote:
On Fri, 13 Jun 2025, Alex Elder wrote:
Add support for SpacemiT PMICs. Initially only the P1 PMIC is supported
but the driver is structured to allow support for others to be added.
The P1 PMIC is controlled by I2C, and is normally implemented with the
SpacemiT K1 SoC. This PMIC provides six buck converters and 12 LDO
six or 12. Please pick a format and remain consistent.
"Numbers smaller than ten should be spelled out."
But I'll use 6 and 12.
regulators. It also implements a switch, watchdog timer, real-time clock,
and more, but initially we will only support its regulators.
You have to provide support for more than one device for this to be
accepted into MFD.
OK. I'm looking at the other device functions to see if I
can pick the easiest one.
Signed-off-by: Alex Elder <elder@xxxxxxxxxxxx>
---
drivers/mfd/Kconfig | 11 +++++
drivers/mfd/Makefile | 1 +
drivers/mfd/spacemit-pmic.c | 91 +++++++++++++++++++++++++++++++++++++
3 files changed, 103 insertions(+)
create mode 100644 drivers/mfd/spacemit-pmic.c
diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index 6fb3768e3d71c..c59ae6cc2dd8d 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -1182,6 +1182,17 @@ config MFD_QCOM_RPM
Say M here if you want to include support for the Qualcomm RPM as a
module. This will build a module called "qcom_rpm".
+config MFD_SPACEMIT_PMIC
+ tristate "SpacemiT PMIC"
+ depends on ARCH_SPACEMIT || COMPILE_TEST
+ depends on I2C && OF
+ select MFD_CORE
+ select REGMAP_I2C
+ default ARCH_SPACEMIT
+ help
+ This option enables support for SpacemiT I2C based PMICs. At
+ this time only the P1 PMIC (used with the K1 SoC) is supported.
+
config MFD_SPMI_PMIC
tristate "Qualcomm SPMI PMICs"
depends on ARCH_QCOM || COMPILE_TEST
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index 79495f9f3457b..59d1ec8db3a3f 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -266,6 +266,7 @@ obj-$(CONFIG_MFD_SUN4I_GPADC) += sun4i-gpadc.o
obj-$(CONFIG_MFD_STM32_LPTIMER) += stm32-lptimer.o
obj-$(CONFIG_MFD_STM32_TIMERS) += stm32-timers.o
obj-$(CONFIG_MFD_MXS_LRADC) += mxs-lradc.o
+obj-$(CONFIG_MFD_SPACEMIT_PMIC) += spacemit-pmic.o
obj-$(CONFIG_MFD_SC27XX_PMIC) += sprd-sc27xx-spi.o
obj-$(CONFIG_RAVE_SP_CORE) += rave-sp.o
obj-$(CONFIG_MFD_ROHM_BD71828) += rohm-bd71828.o
diff --git a/drivers/mfd/spacemit-pmic.c b/drivers/mfd/spacemit-pmic.c
new file mode 100644
index 0000000000000..7c3c3e27236da
--- /dev/null
+++ b/drivers/mfd/spacemit-pmic.c
@@ -0,0 +1,91 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2025 by RISCstar Solutions Corporation. All rights reserved.
+ * Derived from code from:
+ * Copyright (C) 2024 Troy Mitchell <troymitchell988@xxxxxxxxx>
+ */
+
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/mfd/core.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/regmap.h>
+#include <linux/types.h>
+
+struct spacemit_pmic_data {
s/data/ddata/
I hadn't noticed that convention. I'll use it.
+ const struct regmap_config *regmap_config;
+ const struct mfd_cell *mfd_cells; /* array */
Hmm ... this is a red flag. Let's see.
+ size_t mfd_cell_count;
+};
+
+static const struct regmap_config p1_regmap_config = {
+ .reg_bits = 8,
+ .val_bits = 8,
+ .max_register = 0xaa,
+};
+
+/* The name field defines the *driver* name that should bind to the device */
This comment is superfluous.
I'll delete it.
I was expecting the driver to recognize the device, not
the device specifying what driver to use, but I guess
I'm used to the DT model.
+static const struct mfd_cell p1_cells[] = {
+ {
+ .name = "spacemit-p1-regulator",
This spacing is wonky. Take a look at all the other drivers here.
Also, you probably want to use MFD_CELL_NAME().
Yes, I see that does what I want.
One is not enough.
+ },
+};
+
+static const struct spacemit_pmic_data p1_pmic_data = {
+ .regmap_config = &p1_regmap_config,
+ .mfd_cells = p1_cells,
+ .mfd_cell_count = ARRAY_SIZE(p1_cells),
+};
+
+static int spacemit_pmic_probe(struct i2c_client *client)
+{
+ const struct spacemit_pmic_data *data;
+ struct device *dev = &client->dev;
+ struct regmap *regmap;
+
+ /* We currently have no need for a device-specific structure */
Then why are we adding one?
I don't understand, but it might be moot once I add support
for another (sub)device.
+ data = of_device_get_match_data(dev);
+ regmap = devm_regmap_init_i2c(client, data->regmap_config);
+ if (IS_ERR(regmap))
+ return dev_err_probe(dev, PTR_ERR(regmap),
+ "regmap initialization failed");
+
+ return devm_mfd_add_devices(dev, PLATFORM_DEVID_AUTO,
+ data->mfd_cells, data->mfd_cell_count,
+ NULL, 0, NULL);
+}
+
+static const struct of_device_id spacemit_pmic_match[] = {
+ {
+ .compatible = "spacemit,p1",
+ .data = &p1_pmic_data,
Ah, now I see.
We do not allow one data from registration mechanism (MFD) to be piped
through another (OF). If you have to match platform data to device (you
don't), then pass through identifiers and match on those in a switch()
statement instead.
I haven't done an MFD driver before and it took some time
to get this working. I'll tell you what led me to it.
I used code posted by Troy Mitchell (plus downstream) as a
starting point.
https://lore.kernel.org/lkml/20241230-k1-p1-v1-0-aa4e02b9f993@xxxxxxxxx/
Krzysztof Kozlowski made this comment on Troy's DT binding:
Drop compatible, regulators are not re-usable blocks.
So my goal was to have the PMIC regulators get bound to a
driver without specifying a DT compatible string, and I
found this worked.
You say I don't need to match platform data to device, but
if I did I would pass through identifiers. Can you refer
me to an example of code that correctly does what I should
be doing instead?
One other comment/question:
This driver is structured as if it could support a different
PMIC (in addition to P1). Should I *not* do that, and simply
make a source file hard-coded for this one PMIC?
+ },
+ { }
+};
+MODULE_DEVICE_TABLE(of, spacemit_pmic_match);
+
+static struct i2c_driver spacemit_pmic_i2c_driver = {
+ .driver = {
+ .name = "spacemit-pmic",
+ .of_match_table = spacemit_pmic_match,
+ },
+ .probe = spacemit_pmic_probe,
Remove these odd tabs please.
OK.
+};
+
+static int __init spacemit_pmic_init(void)
+{
+ return i2c_add_driver(&spacemit_pmic_i2c_driver);
+}
+
+static void __exit spacemit_pmic_exit(void)
+{
+ i2c_del_driver(&spacemit_pmic_i2c_driver);
+}
+
Remove this line.
Sure.
+module_init(spacemit_pmic_init);
+module_exit(spacemit_pmic_exit);
Are you sure there isn't some boiler plate to do all of this?
Ah ha:
module_i2c_driver()
Thanks for Googling that for me. And thank you very much
for the review.
-Alex
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("SpacemiT multi-function PMIC driver");
--
2.45.2