i2c: pasemi: Add Apple platform driver

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>
Acked-by: Olof Johansson <olof@lixom.net>
Tested-by: Christian Zigotzky <chzigotzky@xenosoft.de>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index 1df19cc..dce3928 100644 (file)
--- 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 0ab1b4c..d85899f 100644 (file)
--- 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 (file)
index 0000000..88a54aa
--- /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");