Re: [PATCH v4 4/6] mfd: lochnagar: Add support for the Cirrus Logic Lochnagar

Lochnagar is an evaluation and development board for Cirrus
Logic Smart CODEC and Amp devices. It allows the connection of
most Cirrus Logic devices on mini-cards, as well as allowing
connection of various application processor systems to provide a
full evaluation platform. This driver supports the board
controller chip on the Lochnagar board. Audio system topology,
clocking and power can all be controlled through the Lochnagar
controller chip, allowing the device under test to be used in
a variety of possible use cases.

As the Lochnagar is a fairly complex device this MFD driver
allows the drivers for the various features to be bound
in. Initially clocking, regulator and pinctrl will be added as
these are necessary to configure the system. But in time at least
audio and voltage/current monitoring will also be added.

Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
---

Changes since v3:
 - Bind in child drivers through device tree rather than using mfd_add_devices
 - Remove defaults arrays for regmap
 - Use a lot of ... in the regmap readable/volatile callbacks
 - Explicitly include register headers, rather than relying on lochnagar.h
 - Add some kernel doc
 - Some minor cosmetic fixups
 - Add a lockdep_assert in lochnagar_update_config

Thanks,
Charles

 MAINTAINERS                         |  17 ++
 drivers/mfd/Kconfig                 |   8 +
 drivers/mfd/Makefile                |   2 +
 drivers/mfd/lochnagar-i2c.c         | 394 ++++++++++++++++++++++++++++++++++++
 include/linux/mfd/lochnagar.h       |  55 +++++
 include/linux/mfd/lochnagar1_regs.h | 157 ++++++++++++++
 include/linux/mfd/lochnagar2_regs.h | 253 +++++++++++++++++++++++
 7 files changed, 886 insertions(+)
 create mode 100644 drivers/mfd/lochnagar-i2c.c
 create mode 100644 include/linux/mfd/lochnagar.h
 create mode 100644 include/linux/mfd/lochnagar1_regs.h
 create mode 100644 include/linux/mfd/lochnagar2_regs.h

diff --git a/MAINTAINERS b/MAINTAINERS
index f4855974f3250..0398c8752e610 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS

@@ -3567,6 +3567,23 @@ L:	netdev@vger.kernel.org
 S:	Maintained
 F:	drivers/net/ethernet/cirrus/ep93xx_eth.c
 
+CIRRUS LOGIC LOCHNAGAR DRIVER
+M:	Charles Keepax <ckeepax@opensource.cirrus.com>
+M:	Richard Fitzgerald <rf@opensource.cirrus.com>
+L:	patches@opensource.cirrus.com
+S:	Supported
+F:	drivers/clk/clk-lochnagar.c
+F:	drivers/mfd/lochnagar-i2c.c
+F:	drivers/pinctrl/cirrus/pinctrl-lochnagar*
+F:	drivers/regulator/lochnagar-regulator.c
+F:	include/dt-bindings/clk/lochnagar.h
+F:	include/dt-bindings/pinctrl/lochnagar.h
+F:	include/linux/mfd/lochnagar*
+F:	Documentation/devicetree/bindings/mfd/cirrus,lochnagar.txt
+F:	Documentation/devicetree/bindings/clock/cirrus,lochnagar.txt
+F:	Documentation/devicetree/bindings/pinctrl/cirrus,lochnagar.txt
+F:	Documentation/devicetree/bindings/regulator/cirrus,lochnagar.txt
+
 CISCO FCOE HBA DRIVER
 M:	Satish Kharat <satishkh@cisco.com>
 M:	Sesidhar Baddela <sebaddel@cisco.com>

diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index 8c5dfdce4326c..51de2db3f6537 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig

@@ -1685,6 +1685,14 @@ config MFD_VX855
 	  VIA VX855/VX875 south bridge. You will need to enable the vx855_spi
 	  and/or vx855_gpio drivers for this to do anything useful.
 
+config MFD_LOCHNAGAR
+	bool "Cirrus Logic Lochnagar Audio Development Board"
+	select MFD_CORE
+	select REGMAP_I2C
+	depends on I2C=y && OF
+	help
+	  Support for Cirrus Logic Lochnagar audio development board.
+
 config MFD_ARIZONA
 	select REGMAP
 	select REGMAP_IRQ

diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index 12980a4ad4608..93284316d5307 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile

@@ -37,6 +37,8 @@ obj-$(CONFIG_MFD_T7L66XB)	+= t7l66xb.o tmio_core.o
 obj-$(CONFIG_MFD_TC6387XB)	+= tc6387xb.o tmio_core.o
 obj-$(CONFIG_MFD_TC6393XB)	+= tc6393xb.o tmio_core.o
 
+obj-$(CONFIG_MFD_LOCHNAGAR)	+= lochnagar-i2c.o
+
 obj-$(CONFIG_MFD_ARIZONA)	+= arizona-core.o
 obj-$(CONFIG_MFD_ARIZONA)	+= arizona-irq.o
 obj-$(CONFIG_MFD_ARIZONA_I2C)	+= arizona-i2c.o

diff --git a/drivers/mfd/lochnagar-i2c.c b/drivers/mfd/lochnagar-i2c.c
new file mode 100644
index 0000000000000..133159d7646ed
--- /dev/null
+++ b/drivers/mfd/lochnagar-i2c.c

@@ -0,0 +1,394 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Lochnagar I2C bus interface
+ *
+ * Copyright (c) 2012-2018 Cirrus Logic, Inc. and
+ *                         Cirrus Logic International Semiconductor Ltd.
+ *
+ * Author: Charles Keepax <ckeepax@opensource.cirrus.com>
+ */
+
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/gpio/consumer.h>
+#include <linux/i2c.h>
+#include <linux/lockdep.h>
+#include <linux/mfd/core.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/regmap.h>
+
+#include <linux/mfd/lochnagar.h>
+#include <linux/mfd/lochnagar1_regs.h>
+#include <linux/mfd/lochnagar2_regs.h>
+
+#define LOCHNAGAR_BOOT_RETRIES		10
+#define LOCHNAGAR_BOOT_DELAY_MS		350
+
+#define LOCHNAGAR_CONFIG_POLL_US	10000
+
+static bool lochnagar1_readable_register(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case LOCHNAGAR_SOFTWARE_RESET:
+	case LOCHNAGAR_FIRMWARE_ID1...LOCHNAGAR_FIRMWARE_ID2:
+	case LOCHNAGAR1_CDC_AIF1_SEL...LOCHNAGAR1_CDC_AIF3_SEL:
+	case LOCHNAGAR1_CDC_MCLK1_SEL...LOCHNAGAR1_CDC_MCLK2_SEL:
+	case LOCHNAGAR1_CDC_AIF_CTRL1...LOCHNAGAR1_CDC_AIF_CTRL2:
+	case LOCHNAGAR1_EXT_AIF_CTRL:
+	case LOCHNAGAR1_DSP_AIF1_SEL...LOCHNAGAR1_DSP_AIF2_SEL:
+	case LOCHNAGAR1_DSP_CLKIN_SEL:
+	case LOCHNAGAR1_DSP_AIF:
+	case LOCHNAGAR1_GF_AIF1...LOCHNAGAR1_GF_AIF2:
+	case LOCHNAGAR1_PSIA_AIF:
+	case LOCHNAGAR1_PSIA1_SEL...LOCHNAGAR1_PSIA2_SEL:
+	case LOCHNAGAR1_SPDIF_AIF_SEL:
+	case LOCHNAGAR1_GF_AIF3_SEL...LOCHNAGAR1_GF_AIF4_SEL:
+	case LOCHNAGAR1_GF_CLKOUT1_SEL:
+	case LOCHNAGAR1_GF_AIF1_SEL...LOCHNAGAR1_GF_AIF2_SEL:
+	case LOCHNAGAR1_GF_GPIO2...LOCHNAGAR1_GF_GPIO7:
+	case LOCHNAGAR1_RST:
+	case LOCHNAGAR1_LED1...LOCHNAGAR1_LED2:
+	case LOCHNAGAR1_I2C_CTRL:
+		return true;
+	default:
+		return false;
+	}
+}