arch: Remove Itanium (IA-64) architecture

The Itanium architecture is obsolete, and an informal survey [0] reveals
that any residual use of Itanium hardware in production is mostly HP-UX
or OpenVMS based. The use of Linux on Itanium appears to be limited to
enthusiasts that occasionally boot a fresh Linux kernel to see whether
things are still working as intended, and perhaps to churn out some
distro packages that are rarely used in practice.

None of the original companies behind Itanium still produce or support
any hardware or software for the architecture, and it is listed as
'Orphaned' in the MAINTAINERS file, as apparently, none of the engineers
that contributed on behalf of those companies (nor anyone else, for that
matter) have been willing to support or maintain the architecture
upstream or even be responsible for applying the odd fix. The Intel
firmware team removed all IA-64 support from the Tianocore/EDK2
reference implementation of EFI in 2018. (Itanium is the original
architecture for which EFI was developed, and the way Linux supports it
deviates significantly from other architectures.) Some distros, such as
Debian and Gentoo, still maintain [unofficial] ia64 ports, but many have
dropped support years ago.

While the argument is being made [1] that there is a 'for the common
good' angle to being able to build and run existing projects such as the
Grid Community Toolkit [2] on Itanium for interoperability testing, the
fact remains that none of those projects are known to be deployed on
Linux/ia64, and very few people actually have access to such a system in
the first place. Even if there were ways imaginable in which Linux/ia64
could be put to good use today, what matters is whether anyone is
actually doing that, and this does not appear to be the case.

There are no emulators widely available, and so boot testing Itanium is
generally infeasible for ordinary contributors. GCC still supports IA-64
but its compile farm [3] no longer has any IA-64 machines. GLIBC would
like to get rid of IA-64 [4] too because it would permit some overdue
code cleanups. In summary, the benefits to the ecosystem of having IA-64
be part of it are mostly theoretical, whereas the maintenance overhead
of keeping it supported is real.

So let's rip off the band aid, and remove the IA-64 arch code entirely.
This follows the timeline proposed by the Debian/ia64 maintainer [5],
which removes support in a controlled manner, leaving IA-64 in a known
good state in the most recent LTS release. Other projects will follow
once the kernel support is removed.

[0] https://lore.kernel.org/all/CAMj1kXFCMh_578jniKpUtx_j8ByHnt=s7S+yQ+vGbKt9ud7+kQ@mail.gmail.com/
[1] https://lore.kernel.org/all/0075883c-7c51-00f5-2c2d-5119c1820410@web.de/
[2] https://gridcf.org/gct-docs/latest/index.html
[3] https://cfarm.tetaneutral.net/machines/list/
[4] https://lore.kernel.org/all/87bkiilpc4.fsf@mid.deneb.enyo.de/
[5] https://lore.kernel.org/all/ff58a3e76e5102c94bb5946d99187b358def688a.camel@physik.fu-berlin.de/

Acked-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

3 files changed, 0 insertions, 365 deletions

diff --git a/drivers/cpufreq/Kconfig b/drivers/cpufreq/Kconfig
index f429b9b37b76..35efb53d5492 100644
--- a/drivers/cpufreq/Kconfig
+++ b/drivers/cpufreq/Kconfig
@@ -239,17 +239,6 @@ if PPC32 || PPC64
 source "drivers/cpufreq/Kconfig.powerpc"
 endif
 
-if IA64
-config IA64_ACPI_CPUFREQ
-	tristate "ACPI Processor P-States driver"
-	depends on ACPI_PROCESSOR
-	help
-	This driver adds a CPUFreq driver which utilizes the ACPI
-	Processor Performance States.
-
-	If in doubt, say N.
-endif
-
 if MIPS
 config BMIPS_CPUFREQ
 	tristate "BMIPS CPUfreq Driver"
diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
index ef8510774913..8d141c71b016 100644
--- a/drivers/cpufreq/Makefile
+++ b/drivers/cpufreq/Makefile
@@ -102,7 +102,6 @@ obj-$(CONFIG_POWERNV_CPUFREQ)		+= powernv-cpufreq.o
 ##################################################################################
 # Other platform drivers
 obj-$(CONFIG_BMIPS_CPUFREQ)		+= bmips-cpufreq.o
-obj-$(CONFIG_IA64_ACPI_CPUFREQ)		+= ia64-acpi-cpufreq.o
 obj-$(CONFIG_LOONGSON2_CPUFREQ)		+= loongson2_cpufreq.o
 obj-$(CONFIG_SH_CPU_FREQ)		+= sh-cpufreq.o
 obj-$(CONFIG_SPARC_US2E_CPUFREQ)	+= sparc-us2e-cpufreq.o
diff --git a/drivers/cpufreq/ia64-acpi-cpufreq.c b/drivers/cpufreq/ia64-acpi-cpufreq.c
deleted file mode 100644
index c6bdc455517f..000000000000
--- a/drivers/cpufreq/ia64-acpi-cpufreq.c
+++ /dev/null
@@ -1,353 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-only
-/*
- * This file provides the ACPI based P-state support. This
- * module works with generic cpufreq infrastructure. Most of
- * the code is based on i386 version
- * (arch/i386/kernel/cpu/cpufreq/acpi-cpufreq.c)
- *
- * Copyright (C) 2005 Intel Corp
- *      Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
- */
-
-#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
-
-#include <linux/kernel.h>
-#include <linux/slab.h>
-#include <linux/module.h>
-#include <linux/init.h>
-#include <linux/cpufreq.h>
-#include <linux/proc_fs.h>
-#include <asm/io.h>
-#include <linux/uaccess.h>
-#include <asm/pal.h>
-
-#include <linux/acpi.h>
-#include <acpi/processor.h>
-
-MODULE_AUTHOR("Venkatesh Pallipadi");
-MODULE_DESCRIPTION("ACPI Processor P-States Driver");
-MODULE_LICENSE("GPL");
-
-struct cpufreq_acpi_io {
-	struct acpi_processor_performance	acpi_data;
-	unsigned int				resume;
-};
-
-struct cpufreq_acpi_req {
-	unsigned int		cpu;
-	unsigned int		state;
-};
-
-static struct cpufreq_acpi_io	*acpi_io_data[NR_CPUS];
-
-static struct cpufreq_driver acpi_cpufreq_driver;
-
-
-static int
-processor_set_pstate (
-	u32	value)
-{
-	s64 retval;
-
-	pr_debug("processor_set_pstate\n");
-
-	retval = ia64_pal_set_pstate((u64)value);
-
-	if (retval) {
-		pr_debug("Failed to set freq to 0x%x, with error 0x%llx\n",
-		        value, retval);
-		return -ENODEV;
-	}
-	return (int)retval;
-}
-
-
-static int
-processor_get_pstate (
-	u32	*value)
-{
-	u64	pstate_index = 0;
-	s64 	retval;
-
-	pr_debug("processor_get_pstate\n");
-
-	retval = ia64_pal_get_pstate(&pstate_index,
-	                             PAL_GET_PSTATE_TYPE_INSTANT);
-	*value = (u32) pstate_index;
-
-	if (retval)
-		pr_debug("Failed to get current freq with "
-			"error 0x%llx, idx 0x%x\n", retval, *value);
-
-	return (int)retval;
-}
-
-
-/* To be used only after data->acpi_data is initialized */
-static unsigned
-extract_clock (
-	struct cpufreq_acpi_io *data,
-	unsigned value)
-{
-	unsigned long i;
-
-	pr_debug("extract_clock\n");
-
-	for (i = 0; i < data->acpi_data.state_count; i++) {
-		if (value == data->acpi_data.states[i].status)
-			return data->acpi_data.states[i].core_frequency;
-	}
-	return data->acpi_data.states[i-1].core_frequency;
-}
-
-
-static long
-processor_get_freq (
-	void *arg)
-{
-	struct cpufreq_acpi_req *req = arg;
-	unsigned int		cpu = req->cpu;
-	struct cpufreq_acpi_io	*data = acpi_io_data[cpu];
-	u32			value;
-	int			ret;
-
-	pr_debug("processor_get_freq\n");
-	if (smp_processor_id() != cpu)
-		return -EAGAIN;
-
-	/* processor_get_pstate gets the instantaneous frequency */
-	ret = processor_get_pstate(&value);
-	if (ret) {
-		pr_warn("get performance failed with error %d\n", ret);
-		return ret;
-	}
-	return 1000 * extract_clock(data, value);
-}
-
-
-static long
-processor_set_freq (
-	void *arg)
-{
-	struct cpufreq_acpi_req *req = arg;
-	unsigned int		cpu = req->cpu;
-	struct cpufreq_acpi_io	*data = acpi_io_data[cpu];
-	int			ret, state = req->state;
-	u32			value;
-
-	pr_debug("processor_set_freq\n");
-	if (smp_processor_id() != cpu)
-		return -EAGAIN;
-
-	if (state == data->acpi_data.state) {
-		if (unlikely(data->resume)) {
-			pr_debug("Called after resume, resetting to P%d\n", state);
-			data->resume = 0;
-		} else {
-			pr_debug("Already at target state (P%d)\n", state);
-			return 0;
-		}
-	}
-
-	pr_debug("Transitioning from P%d to P%d\n",
-		data->acpi_data.state, state);
-
-	/*
-	 * First we write the target state's 'control' value to the
-	 * control_register.
-	 */
-	value = (u32) data->acpi_data.states[state].control;
-
-	pr_debug("Transitioning to state: 0x%08x\n", value);
-
-	ret = processor_set_pstate(value);
-	if (ret) {
-		pr_warn("Transition failed with error %d\n", ret);
-		return -ENODEV;
-	}
-
-	data->acpi_data.state = state;
-	return 0;
-}
-
-
-static unsigned int
-acpi_cpufreq_get (
-	unsigned int		cpu)
-{
-	struct cpufreq_acpi_req req;
-	long ret;
-
-	req.cpu = cpu;
-	ret = work_on_cpu(cpu, processor_get_freq, &req);
-
-	return ret > 0 ? (unsigned int) ret : 0;
-}
-
-
-static int
-acpi_cpufreq_target (
-	struct cpufreq_policy   *policy,
-	unsigned int index)
-{
-	struct cpufreq_acpi_req req;
-
-	req.cpu = policy->cpu;
-	req.state = index;
-
-	return work_on_cpu(req.cpu, processor_set_freq, &req);
-}
-
-static int
-acpi_cpufreq_cpu_init (
-	struct cpufreq_policy   *policy)
-{
-	unsigned int		i;
-	unsigned int		cpu = policy->cpu;
-	struct cpufreq_acpi_io	*data;
-	unsigned int		result = 0;
-	struct cpufreq_frequency_table *freq_table;
-
-	pr_debug("acpi_cpufreq_cpu_init\n");
-
-	data = kzalloc(sizeof(*data), GFP_KERNEL);
-	if (!data)
-		return (-ENOMEM);
-
-	acpi_io_data[cpu] = data;
-
-	result = acpi_processor_register_performance(&data->acpi_data, cpu);
-
-	if (result)
-		goto err_free;
-
-	/* capability check */
-	if (data->acpi_data.state_count <= 1) {
-		pr_debug("No P-States\n");
-		result = -ENODEV;
-		goto err_unreg;
-	}
-
-	if ((data->acpi_data.control_register.space_id !=
-					ACPI_ADR_SPACE_FIXED_HARDWARE) ||
-	    (data->acpi_data.status_register.space_id !=
-					ACPI_ADR_SPACE_FIXED_HARDWARE)) {
-		pr_debug("Unsupported address space [%d, %d]\n",
-			(u32) (data->acpi_data.control_register.space_id),
-			(u32) (data->acpi_data.status_register.space_id));
-		result = -ENODEV;
-		goto err_unreg;
-	}
-
-	/* alloc freq_table */
-	freq_table = kcalloc(data->acpi_data.state_count + 1,
-	                           sizeof(*freq_table),
-	                           GFP_KERNEL);
-	if (!freq_table) {
-		result = -ENOMEM;
-		goto err_unreg;
-	}
-
-	/* detect transition latency */
-	policy->cpuinfo.transition_latency = 0;
-	for (i=0; i<data->acpi_data.state_count; i++) {
-		if ((data->acpi_data.states[i].transition_latency * 1000) >
-		    policy->cpuinfo.transition_latency) {
-			policy->cpuinfo.transition_latency =
-			    data->acpi_data.states[i].transition_latency * 1000;
-		}
-	}
-
-	/* table init */
-	for (i = 0; i <= data->acpi_data.state_count; i++)
-	{
-		if (i < data->acpi_data.state_count) {
-			freq_table[i].frequency =
-			      data->acpi_data.states[i].core_frequency * 1000;
-		} else {
-			freq_table[i].frequency = CPUFREQ_TABLE_END;
-		}
-	}
-
-	policy->freq_table = freq_table;
-
-	/* notify BIOS that we exist */
-	acpi_processor_notify_smm(THIS_MODULE);
-
-	pr_info("CPU%u - ACPI performance management activated\n", cpu);
-
-	for (i = 0; i < data->acpi_data.state_count; i++)
-		pr_debug("     %cP%d: %d MHz, %d mW, %d uS, %d uS, 0x%x 0x%x\n",
-			(i == data->acpi_data.state?'*':' '), i,
-			(u32) data->acpi_data.states[i].core_frequency,
-			(u32) data->acpi_data.states[i].power,
-			(u32) data->acpi_data.states[i].transition_latency,
-			(u32) data->acpi_data.states[i].bus_master_latency,
-			(u32) data->acpi_data.states[i].status,
-			(u32) data->acpi_data.states[i].control);
-
-	/* the first call to ->target() should result in us actually
-	 * writing something to the appropriate registers. */
-	data->resume = 1;
-
-	return (result);
-
- err_unreg:
-	acpi_processor_unregister_performance(cpu);
- err_free:
-	kfree(data);
-	acpi_io_data[cpu] = NULL;
-
-	return (result);
-}
-
-
-static int
-acpi_cpufreq_cpu_exit (
-	struct cpufreq_policy   *policy)
-{
-	struct cpufreq_acpi_io *data = acpi_io_data[policy->cpu];
-
-	pr_debug("acpi_cpufreq_cpu_exit\n");
-
-	if (data) {
-		acpi_io_data[policy->cpu] = NULL;
-		acpi_processor_unregister_performance(policy->cpu);
-		kfree(policy->freq_table);
-		kfree(data);
-	}
-
-	return (0);
-}
-
-
-static struct cpufreq_driver acpi_cpufreq_driver = {
-	.verify 	= cpufreq_generic_frequency_table_verify,
-	.target_index	= acpi_cpufreq_target,
-	.get 		= acpi_cpufreq_get,
-	.init		= acpi_cpufreq_cpu_init,
-	.exit		= acpi_cpufreq_cpu_exit,
-	.name		= "acpi-cpufreq",
-	.attr		= cpufreq_generic_attr,
-};
-
-
-static int __init
-acpi_cpufreq_init (void)
-{
-	pr_debug("acpi_cpufreq_init\n");
-
- 	return cpufreq_register_driver(&acpi_cpufreq_driver);
-}
-
-
-static void __exit
-acpi_cpufreq_exit (void)
-{
-	pr_debug("acpi_cpufreq_exit\n");
-
-	cpufreq_unregister_driver(&acpi_cpufreq_driver);
-}
-
-late_initcall(acpi_cpufreq_init);
-module_exit(acpi_cpufreq_exit);