[PATCH v2 10/11] i2c: pasemi: Add Apple platform driver

Sven Peter
2021-10-08T16:37:08Z

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