soc: qcom: ipa: clocking, interrupts, and memory

This patch incorporates three source files (and their headers).  They're
grouped into one patch mainly for the purpose of making the number and
size of patches in this series somewhat reasonable.

  - "ipa_clock.c" and "ipa_clock.h" implement clocking for the IPA device.
    The IPA has a single core clock managed by the common clock framework.
    In addition, the IPA has three buses whose bandwidth is managed by the
    Linux interconnect framework.  At this time the core clock and all
    three buses are either on or off; we don't yet do any more fine-grained
    management than that.  The core clock and interconnects are enabled
    and disabled as a unit, using a unified clock-like abstraction,
    ipa_clock_get()/ipa_clock_put().

  - "ipa_interrupt.c" and "ipa_interrupt.h" implement IPA interrupts.
    There are two hardware IRQs used by the IPA driver (the other is
    the GSI interrupt, described in a separate patch).  Several types
    of interrupt are handled by the IPA IRQ handler; these are not part
    of data/fast path.

  - The IPA has a region of local memory that is accessible by the AP
    (and modem).  Within that region are areas with certain defined
    purposes.  "ipa_mem.c" and "ipa_mem.h" define those regions, and
    implement their initialization.

Signed-off-by: Alex Elder <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

Author: Alex Elder

drivers/net/ipa/ipa_clock.c

@@ -0,0 +1,313 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/* Copyright (c) 2012-2018, The Linux Foundation. All rights reserved.
+ * Copyright (C) 2018-2020 Linaro Ltd.
+ */
+
+#include <linux/atomic.h>
+#include <linux/mutex.h>
+#include <linux/clk.h>
+#include <linux/device.h>
+#include <linux/interconnect.h>
+
+#include "ipa.h"
+#include "ipa_clock.h"
+#include "ipa_modem.h"
+
+/**
+ * DOC: IPA Clocking
+ *
+ * The "IPA Clock" manages both the IPA core clock and the interconnects
+ * (buses) the IPA depends on as a single logical entity.  A reference count
+ * is incremented by "get" operations and decremented by "put" operations.
+ * Transitions of that count from 0 to 1 result in the clock and interconnects
+ * being enabled, and transitions of the count from 1 to 0 cause them to be
+ * disabled.  We currently operate the core clock at a fixed clock rate, and
+ * all buses at a fixed average and peak bandwidth.  As more advanced IPA
+ * features are enabled, we can make better use of clock and bus scaling.
+ *
+ * An IPA clock reference must be held for any access to IPA hardware.
+ */
+
+#define	IPA_CORE_CLOCK_RATE		(75UL * 1000 * 1000)	/* Hz */
+
+/* Interconnect path bandwidths (each times 1000 bytes per second) */
+#define IPA_MEMORY_AVG			(80 * 1000)	/* 80 MBps */
+#define IPA_MEMORY_PEAK			(600 * 1000)
+
+#define IPA_IMEM_AVG			(80 * 1000)
+#define IPA_IMEM_PEAK			(350 * 1000)
+
+#define IPA_CONFIG_AVG			(40 * 1000)
+#define IPA_CONFIG_PEAK			(40 * 1000)
+
+/**
+ * struct ipa_clock - IPA clocking information
+ * @count:		Clocking reference count
+ * @mutex;		Protects clock enable/disable
+ * @core:		IPA core clock
+ * @memory_path:	Memory interconnect
+ * @imem_path:		Internal memory interconnect
+ * @config_path:	Configuration space interconnect
+ */
+struct ipa_clock {
+	atomic_t count;
+	struct mutex mutex; /* protects clock enable/disable */
+	struct clk *core;
+	struct icc_path *memory_path;
+	struct icc_path *imem_path;
+	struct icc_path *config_path;
+};
+
+static struct icc_path *
+ipa_interconnect_init_one(struct device *dev, const char *name)
+{
+	struct icc_path *path;
+
+	path = of_icc_get(dev, name);
+	if (IS_ERR(path))
+		dev_err(dev, "error %ld getting memory interconnect\n",
+			PTR_ERR(path));
+
+	return path;
+}
+
+/* Initialize interconnects required for IPA operation */
+static int ipa_interconnect_init(struct ipa_clock *clock, struct device *dev)
+{
+	struct icc_path *path;
+
+	path = ipa_interconnect_init_one(dev, "memory");
+	if (IS_ERR(path))
+		goto err_return;
+	clock->memory_path = path;
+
+	path = ipa_interconnect_init_one(dev, "imem");
+	if (IS_ERR(path))
+		goto err_memory_path_put;
+	clock->imem_path = path;
+
+	path = ipa_interconnect_init_one(dev, "config");
+	if (IS_ERR(path))
+		goto err_imem_path_put;
+	clock->config_path = path;
+
+	return 0;
+
+err_imem_path_put:
+	icc_put(clock->imem_path);
+err_memory_path_put:
+	icc_put(clock->memory_path);
+err_return:
+	return PTR_ERR(path);
+}
+
+/* Inverse of ipa_interconnect_init() */
+static void ipa_interconnect_exit(struct ipa_clock *clock)
+{
+	icc_put(clock->config_path);
+	icc_put(clock->imem_path);
+	icc_put(clock->memory_path);
+}
+
+/* Currently we only use one bandwidth level, so just "enable" interconnects */
+static int ipa_interconnect_enable(struct ipa *ipa)
+{
+	struct ipa_clock *clock = ipa->clock;
+	int ret;
+
+	ret = icc_set_bw(clock->memory_path, IPA_MEMORY_AVG, IPA_MEMORY_PEAK);
+	if (ret)
+		return ret;
+
+	ret = icc_set_bw(clock->imem_path, IPA_IMEM_AVG, IPA_IMEM_PEAK);
+	if (ret)
+		goto err_memory_path_disable;
+
+	ret = icc_set_bw(clock->config_path, IPA_CONFIG_AVG, IPA_CONFIG_PEAK);
+	if (ret)
+		goto err_imem_path_disable;
+
+	return 0;
+
+err_imem_path_disable:
+	(void)icc_set_bw(clock->imem_path, 0, 0);
+err_memory_path_disable:
+	(void)icc_set_bw(clock->memory_path, 0, 0);
+
+	return ret;
+}
+
+/* To disable an interconnect, we just its bandwidth to 0 */
+static int ipa_interconnect_disable(struct ipa *ipa)
+{
+	struct ipa_clock *clock = ipa->clock;
+	int ret;
+
+	ret = icc_set_bw(clock->memory_path, 0, 0);
+	if (ret)
+		return ret;
+
+	ret = icc_set_bw(clock->imem_path, 0, 0);
+	if (ret)
+		goto err_memory_path_reenable;
+
+	ret = icc_set_bw(clock->config_path, 0, 0);
+	if (ret)
+		goto err_imem_path_reenable;
+
+	return 0;
+
+err_imem_path_reenable:
+	(void)icc_set_bw(clock->imem_path, IPA_IMEM_AVG, IPA_IMEM_PEAK);
+err_memory_path_reenable:
+	(void)icc_set_bw(clock->memory_path, IPA_MEMORY_AVG, IPA_MEMORY_PEAK);
+
+	return ret;
+}
+
+/* Turn on IPA clocks, including interconnects */
+static int ipa_clock_enable(struct ipa *ipa)
+{
+	int ret;
+
+	ret = ipa_interconnect_enable(ipa);
+	if (ret)
+		return ret;
+
+	ret = clk_prepare_enable(ipa->clock->core);
+	if (ret)
+		ipa_interconnect_disable(ipa);
+
+	return ret;
+}
+
+/* Inverse of ipa_clock_enable() */
+static void ipa_clock_disable(struct ipa *ipa)
+{
+	clk_disable_unprepare(ipa->clock->core);
+	(void)ipa_interconnect_disable(ipa);
+}
+
+/* Get an IPA clock reference, but only if the reference count is
+ * already non-zero.  Returns true if the additional reference was
+ * added successfully, or false otherwise.
+ */
+bool ipa_clock_get_additional(struct ipa *ipa)
+{
+	return !!atomic_inc_not_zero(&ipa->clock->count);
+}
+
+/* Get an IPA clock reference.  If the reference count is non-zero, it is
+ * incremented and return is immediate.  Otherwise it is checked again
+ * under protection of the mutex, and if appropriate the clock (and
+ * interconnects) are enabled suspended endpoints (if any) are resumed
+ * before returning.
+ *
+ * Incrementing the reference count is intentionally deferred until
+ * after the clock is running and endpoints are resumed.
+ */
+void ipa_clock_get(struct ipa *ipa)
+{
+	struct ipa_clock *clock = ipa->clock;
+	int ret;
+
+	/* If the clock is running, just bump the reference count */
+	if (ipa_clock_get_additional(ipa))
+		return;
+
+	/* Otherwise get the mutex and check again */
+	mutex_lock(&clock->mutex);
+
+	/* A reference might have been added before we got the mutex. */
+	if (ipa_clock_get_additional(ipa))
+		goto out_mutex_unlock;
+
+	ret = ipa_clock_enable(ipa);
+	if (ret) {
+		dev_err(&ipa->pdev->dev, "error %d enabling IPA clock\n", ret);
+		goto out_mutex_unlock;
+	}
+
+	ipa_endpoint_resume(ipa);
+
+	atomic_inc(&clock->count);
+
+out_mutex_unlock:
+	mutex_unlock(&clock->mutex);
+}
+
+/* Attempt to remove an IPA clock reference.  If this represents the last
+ * reference, suspend endpoints and disable the clock (and interconnects)
+ * under protection of a mutex.
+ */
+void ipa_clock_put(struct ipa *ipa)
+{
+	struct ipa_clock *clock = ipa->clock;
+
+	/* If this is not the last reference there's nothing more to do */
+	if (!atomic_dec_and_mutex_lock(&clock->count, &clock->mutex))
+		return;
+
+	ipa_endpoint_suspend(ipa);
+
+	ipa_clock_disable(ipa);
+
+	mutex_unlock(&clock->mutex);
+}
+
+/* Initialize IPA clocking */
+struct ipa_clock *ipa_clock_init(struct device *dev)
+{
+	struct ipa_clock *clock;
+	struct clk *clk;
+	int ret;
+
+	clk = clk_get(dev, "core");
+	if (IS_ERR(clk)) {
+		dev_err(dev, "error %ld getting core clock\n", PTR_ERR(clk));
+		return ERR_CAST(clk);
+	}
+
+	ret = clk_set_rate(clk, IPA_CORE_CLOCK_RATE);
+	if (ret) {
+		dev_err(dev, "error %d setting core clock rate to %lu\n",
+			ret, IPA_CORE_CLOCK_RATE);
+		goto err_clk_put;
+	}
+
+	clock = kzalloc(sizeof(*clock), GFP_KERNEL);
+	if (!clock) {
+		ret = -ENOMEM;
+		goto err_clk_put;
+	}
+	clock->core = clk;
+
+	ret = ipa_interconnect_init(clock, dev);
+	if (ret)
+		goto err_kfree;
+
+	mutex_init(&clock->mutex);
+	atomic_set(&clock->count, 0);
+
+	return clock;
+
+err_kfree:
+	kfree(clock);
+err_clk_put:
+	clk_put(clk);
+
+	return ERR_PTR(ret);
+}
+
+/* Inverse of ipa_clock_init() */
+void ipa_clock_exit(struct ipa_clock *clock)
+{
+	struct clk *clk = clock->core;
+
+	WARN_ON(atomic_read(&clock->count) != 0);
+	mutex_destroy(&clock->mutex);
+	ipa_interconnect_exit(clock);
+	kfree(clock);
+	clk_put(clk);
+}

drivers/net/ipa/ipa_clock.h

@@ -0,0 +1,53 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+/* Copyright (c) 2012-2018, The Linux Foundation. All rights reserved.
+ * Copyright (C) 2018-2020 Linaro Ltd.
+ */
+#ifndef _IPA_CLOCK_H_
+#define _IPA_CLOCK_H_
+
+struct device;
+
+struct ipa;
+
+/**
+ * ipa_clock_init() - Initialize IPA clocking
+ * @dev:	IPA device
+ *
+ * @Return:	A pointer to an ipa_clock structure, or a pointer-coded error
+ */
+struct ipa_clock *ipa_clock_init(struct device *dev);
+
+/**
+ * ipa_clock_exit() - Inverse of ipa_clock_init()
+ * @clock:	IPA clock pointer
+ */
+void ipa_clock_exit(struct ipa_clock *clock);
+
+/**
+ * ipa_clock_get() - Get an IPA clock reference
+ * @ipa:	IPA pointer
+ *
+ * This call blocks if this is the first reference.
+ */
+void ipa_clock_get(struct ipa *ipa);
+
+/**
+ * ipa_clock_get_additional() - Get an IPA clock reference if not first
+ * @ipa:	IPA pointer
+ *
+ * This returns immediately, and only takes a reference if not the first
+ */
+bool ipa_clock_get_additional(struct ipa *ipa);
+
+/**
+ * ipa_clock_put() - Drop an IPA clock reference
+ * @ipa:	IPA pointer
+ *
+ * This drops a clock reference.  If the last reference is being dropped,
+ * the clock is stopped and RX endpoints are suspended.  This call will
+ * not block unless the last reference is dropped.
+ */
+void ipa_clock_put(struct ipa *ipa);
+
+#endif /* _IPA_CLOCK_H_ */