Commit a722de30 authored by Sven Peter's avatar Sven Peter Committed by Vinod Koul
Browse files

soc: apple: Add hardware tunable support 



Various hardware, like the Type-C PHY or the Thunderbolt/USB4 NHI,
present on Apple SoCs need machine-specific tunables passed from our
bootloader m1n1 to the device tree. Add generic helpers so that we
don't have to duplicate this across multiple drivers.

Reviewed-by: default avatarAlyssa Rosenzweig <alyssa@rosenzweig.io>
Reviewed-by: default avatarNeal Gompa <neal@gompa.dev>
Reviewed-by: default avatarJanne Grunau <j@jannau.net>
Signed-off-by: default avatarSven Peter <sven@kernel.org>
Link: https://patch.msgid.link/20251214-b4-atcphy-v3-1-ba82b20e9459@kernel.org


Signed-off-by: default avatarVinod Koul <vkoul@kernel.org>
parent 81791c45

drivers/soc/apple/Kconfig

+4 −0
Original line number Diff line number Diff line
@@ -38,6 +38,10 @@ config APPLE_SART 


	  Say 'y' here if you have an Apple SoC.



config APPLE_TUNABLE

	tristate

	depends on ARCH_APPLE || COMPILE_TEST



endmenu



endif

drivers/soc/apple/Makefile

+3 −0
Original line number Diff line number Diff line
@@ -8,3 +8,6 @@ apple-rtkit-y = rtkit.o rtkit-crashlog.o 


obj-$(CONFIG_APPLE_SART) += apple-sart.o

apple-sart-y = sart.o



obj-$(CONFIG_APPLE_TUNABLE) += apple-tunable.o

apple-tunable-y = tunable.o

drivers/soc/apple/tunable.c

0 → 100644
+80 −0
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// SPDX-License-Identifier: GPL-2.0-only OR MIT

/*

 * Apple Silicon hardware tunable support

 *

 * Each tunable is a list with each entry containing a offset into the MMIO

 * region, a mask of bits to be cleared and a set of bits to be set. These

 * tunables are passed along by the previous boot stages and vary from device

 * to device such that they cannot be hardcoded in the individual drivers.

 *

 * Copyright (C) The Asahi Linux Contributors

 */



#include <linux/io.h>

#include <linux/module.h>

#include <linux/of.h>

#include <linux/overflow.h>

#include <linux/soc/apple/tunable.h>



struct apple_tunable *devm_apple_tunable_parse(struct device *dev,

					       struct device_node *np,

					       const char *name,

					       struct resource *res)

{

	struct apple_tunable *tunable;

	struct property *prop;

	const __be32 *p;

	size_t sz;

	int i;



	if (resource_size(res) < 4)

		return ERR_PTR(-EINVAL);



	prop = of_find_property(np, name, NULL);

	if (!prop)

		return ERR_PTR(-ENOENT);



	if (prop->length % (3 * sizeof(u32)))

		return ERR_PTR(-EINVAL);

	sz = prop->length / (3 * sizeof(u32));



	tunable = devm_kzalloc(dev, struct_size(tunable, values, sz), GFP_KERNEL);

	if (!tunable)

		return ERR_PTR(-ENOMEM);

	tunable->sz = sz;



	for (i = 0, p = NULL; i < tunable->sz; ++i) {

		p = of_prop_next_u32(prop, p, &tunable->values[i].offset);

		p = of_prop_next_u32(prop, p, &tunable->values[i].mask);

		p = of_prop_next_u32(prop, p, &tunable->values[i].value);



		/* Sanity checks to catch bugs in our bootloader */

		if (tunable->values[i].offset % 4)

			return ERR_PTR(-EINVAL);

		if (tunable->values[i].offset > (resource_size(res) - 4))

			return ERR_PTR(-EINVAL);

	}



	return tunable;

}

EXPORT_SYMBOL(devm_apple_tunable_parse);



void apple_tunable_apply(void __iomem *regs, struct apple_tunable *tunable)

{

	size_t i;



	for (i = 0; i < tunable->sz; ++i) {

		u32 val, old_val;



		old_val = readl(regs + tunable->values[i].offset);

		val = old_val & ~tunable->values[i].mask;

		val |= tunable->values[i].value;

		if (val != old_val)

			writel(val, regs + tunable->values[i].offset);

	}

}

EXPORT_SYMBOL(apple_tunable_apply);



MODULE_LICENSE("Dual MIT/GPL");

MODULE_AUTHOR("Sven Peter <sven@kernel.org>");

MODULE_DESCRIPTION("Apple Silicon hardware tunable support");

include/linux/soc/apple/tunable.h

0 → 100644
+62 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0-only OR MIT */

/*

 * Apple Silicon hardware tunable support

 *

 * Each tunable is a list with each entry containing a offset into the MMIO

 * region, a mask of bits to be cleared and a set of bits to be set. These

 * tunables are passed along by the previous boot stages and vary from device

 * to device such that they cannot be hardcoded in the individual drivers.

 *

 * Copyright (C) The Asahi Linux Contributors

 */



#ifndef _LINUX_SOC_APPLE_TUNABLE_H_

#define _LINUX_SOC_APPLE_TUNABLE_H_



#include <linux/device.h>

#include <linux/types.h>



/**

 * Struct to store an Apple Silicon hardware tunable.

 *

 * Each tunable is a list with each entry containing a offset into the MMIO

 * region, a mask of bits to be cleared and a set of bits to be set. These

 * tunables are passed along by the previous boot stages and vary from device

 * to device such that they cannot be hardcoded in the individual drivers.

 *

 * @param sz Number of [offset, mask, value] tuples stored in values.

 * @param values [offset, mask, value] array.

 */

struct apple_tunable {

	size_t sz;

	struct {

		u32 offset;

		u32 mask;

		u32 value;

	} values[] __counted_by(sz);

};



/**

 * Parse an array of hardware tunables from the device tree.

 *

 * @dev: Device node used for devm_kzalloc internally.

 * @np: Device node which contains the tunable array.

 * @name: Name of the device tree property which contains the tunables.

 * @res: Resource to which the tunables will be applied, used for bound checking

 *

 * @return: devres allocated struct on success or PTR_ERR on failure.

 */

struct apple_tunable *devm_apple_tunable_parse(struct device *dev,

					       struct device_node *np,

					       const char *name,

					       struct resource *res);



/**

 * Apply a previously loaded hardware tunable.

 *

 * @param regs: MMIO to which the tunable will be applied.

 * @param tunable: Pointer to the tunable.

 */

void apple_tunable_apply(void __iomem *regs, struct apple_tunable *tunable);



#endif