Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
From:   Sven Peter <sven@svenpeter.dev>
To:     Michael Ellerman <mpe@ellerman.id.au>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Olof Johansson <olof@lixom.net>,
        Christian Zigotzky <chzigotzky@xenosoft.de>,
        Wolfram Sang <wsa@kernel.org>
Cc:     Sven Peter <sven@svenpeter.dev>, Arnd Bergmann <arnd@arndb.de>,
        Hector Martin <marcan@marcan.st>,
        Mohamed Mediouni <mohamed.mediouni@caramail.com>,
        Stan Skowronek <stan@corellium.com>,
        Mark Kettenis <mark.kettenis@xs4all.nl>,
        Alyssa Rosenzweig <alyssa@rosenzweig.io>,
        linux-arm-kernel@lists.infradead.org,
        linuxppc-dev@lists.ozlabs.org, linux-i2c@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: [PATCH v2 10/11] i2c: pasemi: Add Apple platform driver
Date:   Fri,  8 Oct 2021 18:35:31 +0200
Message-Id: <20211008163532.75569-11-sven@svenpeter.dev>
In-Reply-To: <20211008163532.75569-1-sven@svenpeter.dev>
References: <20211008163532.75569-1-sven@svenpeter.dev>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

With all the previous preparations we can now finally add
the platform driver to support the PASemi-based controllers
in Apple SoCs. This does not work on the M1 yet but should
work on the early iPhones already.

Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Sven Peter <sven@svenpeter.dev>
---
v1 -> v2:
 - renamed i2c-pasemi-apple.c to i2c-pasemi-platform.c and adjusted
   function names as well
 - removed unused struct pinctrl *pctrl which snuck into v1

 MAINTAINERS                              |   1 +
 drivers/i2c/busses/Kconfig               |  11 ++
 drivers/i2c/busses/Makefile              |   2 +
 drivers/i2c/busses/i2c-pasemi-platform.c | 122 +++++++++++++++++++++++
 4 files changed, 136 insertions(+)
 create mode 100644 drivers/i2c/busses/i2c-pasemi-platform.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 74aa85967ca3..8e0f1dc94b5b 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1740,6 +1740,7 @@ F:	Documentation/devicetree/bindings/interrupt-controller/apple,aic.yaml
 F:	Documentation/devicetree/bindings/pci/apple,pcie.yaml
 F:	Documentation/devicetree/bindings/pinctrl/apple,pinctrl.yaml
 F:	arch/arm64/boot/dts/apple/
+F:	drivers/i2c/busses/i2c-pasemi-platform.c
 F:	drivers/irqchip/irq-apple-aic.c
 F:	include/dt-bindings/interrupt-controller/apple-aic.h
 F:	include/dt-bindings/pinctrl/apple.h
diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index 1df19ccc310b..dce392839017 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -859,6 +859,17 @@ config I2C_PASEMI
 	help
 	  Supports the PA Semi PWRficient on-chip SMBus interfaces.
 
+config I2C_APPLE
+	tristate "Apple SMBus platform driver"
+	depends on ARCH_APPLE || COMPILE_TEST
+	default ARCH_APPLE
+	help
+	  Say Y here if you want to use the I2C controller present on Apple
+	  Silicon chips such as the M1.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called i2c-apple.
+
 config I2C_PCA_PLATFORM
 	tristate "PCA9564/PCA9665 as platform device"
 	select I2C_ALGOPCA
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index 0ab1b4cb2228..d85899fef8c7 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -86,6 +86,8 @@ obj-$(CONFIG_I2C_OMAP)		+= i2c-omap.o
 obj-$(CONFIG_I2C_OWL)		+= i2c-owl.o
 i2c-pasemi-objs := i2c-pasemi-core.o i2c-pasemi-pci.o
 obj-$(CONFIG_I2C_PASEMI)	+= i2c-pasemi.o
+i2c-apple-objs := i2c-pasemi-core.o i2c-pasemi-platform.o
+obj-$(CONFIG_I2C_APPLE)	+= i2c-apple.o
 obj-$(CONFIG_I2C_PCA_PLATFORM)	+= i2c-pca-platform.o
 obj-$(CONFIG_I2C_PNX)		+= i2c-pnx.o
 obj-$(CONFIG_I2C_PXA)		+= i2c-pxa.o
diff --git a/drivers/i2c/busses/i2c-pasemi-platform.c b/drivers/i2c/busses/i2c-pasemi-platform.c
new file mode 100644
index 000000000000..88a54aaf7e3c
--- /dev/null
+++ b/drivers/i2c/busses/i2c-pasemi-platform.c
@@ -0,0 +1,122 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2021 The Asahi Linux Contributors
+ *
+ * PA Semi PWRficient SMBus host driver for Apple SoCs
+ */
+
+#include <linux/clk.h>
+#include <linux/i2c.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/types.h>
+
+#include "i2c-pasemi-core.h"
+
+struct pasemi_platform_i2c_data {
+	struct pasemi_smbus smbus;
+	struct clk *clk_ref;
+};
+
+static int
+pasemi_platform_i2c_calc_clk_div(struct pasemi_platform_i2c_data *data,
+				 u32 frequency)
+{
+	unsigned long clk_rate = clk_get_rate(data->clk_ref);
+
+	if (!clk_rate)
+		return -EINVAL;
+
+	data->smbus.clk_div = DIV_ROUND_UP(clk_rate, 16 * frequency);
+	if (data->smbus.clk_div < 4)
+		return dev_err_probe(data->smbus.dev, -EINVAL,
+				     "Bus frequency %d is too fast.\n",
+				     frequency);
+	if (data->smbus.clk_div > 0xff)
+		return dev_err_probe(data->smbus.dev, -EINVAL,
+				     "Bus frequency %d is too slow.\n",
+				     frequency);
+
+	return 0;
+}
+
+static int pasemi_platform_i2c_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct pasemi_platform_i2c_data *data;
+	struct pasemi_smbus *smbus;
+	u32 frequency;
+	int error;
+
+	data = devm_kzalloc(dev, sizeof(struct pasemi_platform_i2c_data),
+			    GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	smbus = &data->smbus;
+	smbus->dev = dev;
+
+	smbus->ioaddr = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(smbus->ioaddr))
+		return PTR_ERR(smbus->ioaddr);
+
+	if (of_property_read_u32(dev->of_node, "clock-frequency", &frequency))
+		frequency = I2C_MAX_STANDARD_MODE_FREQ;
+
+	data->clk_ref = devm_clk_get(dev, NULL);
+	if (IS_ERR(data->clk_ref))
+		return PTR_ERR(data->clk_ref);
+
+	error = clk_prepare_enable(data->clk_ref);
+	if (error)
+		return error;
+
+	error = pasemi_platform_i2c_calc_clk_div(data, frequency);
+	if (error)
+		goto out_clk_disable;
+
+	smbus->adapter.dev.of_node = pdev->dev.of_node;
+	error = pasemi_i2c_common_probe(smbus);
+	if (error)
+		goto out_clk_disable;
+
+	platform_set_drvdata(pdev, data);
+
+	return 0;
+
+out_clk_disable:
+	clk_disable_unprepare(data->clk_ref);
+
+	return error;
+}
+
+static int pasemi_platform_i2c_remove(struct platform_device *pdev)
+{
+	struct pasemi_platform_i2c_data *data = platform_get_drvdata(pdev);
+
+	clk_disable_unprepare(data->clk_ref);
+	return 0;
+}
+
+static const struct of_device_id pasemi_platform_i2c_of_match[] = {
+	{ .compatible = "apple,t8103-i2c" },
+	{ .compatible = "apple,i2c" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, pasemi_platform_i2c_of_match);
+
+static struct platform_driver pasemi_platform_i2c_driver = {
+	.driver	= {
+		.name			= "i2c-apple",
+		.of_match_table		= pasemi_platform_i2c_of_match,
+	},
+	.probe	= pasemi_platform_i2c_probe,
+	.remove	= pasemi_platform_i2c_remove,
+};
+module_platform_driver(pasemi_platform_i2c_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Sven Peter <sven@svenpeter.dev>");
+MODULE_DESCRIPTION("Apple/PASemi SMBus platform driver");
-- 
2.25.1