1 files changed, 335 insertions, 0 deletions
diff --git a/drivers/net/ipa/ipa_smp2p.c b/drivers/net/ipa/ipa_smp2p.c
new file mode 100644
index 000000000000..4d33aa7ebfbb
--- /dev/null
+++ b/drivers/net/ipa/ipa_smp2p.c
@@ -0,0 +1,335 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/* Copyright (c) 2012-2018, The Linux Foundation. All rights reserved.
+ * Copyright (C) 2019-2020 Linaro Ltd.
+ */
+
+#include <linux/types.h>
+#include <linux/device.h>
+#include <linux/interrupt.h>
+#include <linux/notifier.h>
+#include <linux/soc/qcom/smem.h>
+#include <linux/soc/qcom/smem_state.h>
+
+#include "ipa_smp2p.h"
+#include "ipa.h"
+#include "ipa_uc.h"
+#include "ipa_clock.h"
+
+/**
+ * DOC: IPA SMP2P communication with the modem
+ *
+ * SMP2P is a primitive communication mechanism available between the AP and
+ * the modem.  The IPA driver uses this for two purposes:  to enable the modem
+ * to state that the GSI hardware is ready to use; and to communicate the
+ * state of the IPA clock in the event of a crash.
+ *
+ * GSI needs to have early initialization completed before it can be used.
+ * This initialization is done either by Trust Zone or by the modem.  In the
+ * latter case, the modem uses an SMP2P interrupt to tell the AP IPA driver
+ * when the GSI is ready to use.
+ *
+ * The modem is also able to inquire about the current state of the IPA
+ * clock by trigging another SMP2P interrupt to the AP.  We communicate
+ * whether the clock is enabled using two SMP2P state bits--one to
+ * indicate the clock state (on or off), and a second to indicate the
+ * clock state bit is valid.  The modem will poll the valid bit until it
+ * is set, and at that time records whether the AP has the IPA clock enabled.
+ *
+ * Finally, if the AP kernel panics, we update the SMP2P state bits even if
+ * we never receive an interrupt from the modem requesting this.
+ */
+
+/**
+ * struct ipa_smp2p - IPA SMP2P information
+ * @ipa:		IPA pointer
+ * @valid_state:	SMEM state indicating enabled state is valid
+ * @enabled_state:	SMEM state to indicate clock is enabled
+ * @valid_bit:		Valid bit in 32-bit SMEM state mask
+ * @enabled_bit:	Enabled bit in 32-bit SMEM state mask
+ * @enabled_bit:	Enabled bit in 32-bit SMEM state mask
+ * @clock_query_irq:	IPA interrupt triggered by modem for clock query
+ * @setup_ready_irq:	IPA interrupt triggered by modem to signal GSI ready
+ * @clock_on:		Whether IPA clock is on
+ * @notified:		Whether modem has been notified of clock state
+ * @disabled:		Whether setup ready interrupt handling is disabled
+ * @mutex mutex:	Motex protecting ready interrupt/shutdown interlock
+ * @panic_notifier:	Panic notifier structure
+*/
+struct ipa_smp2p {
+	struct ipa *ipa;
+	struct qcom_smem_state *valid_state;
+	struct qcom_smem_state *enabled_state;
+	u32 valid_bit;
+	u32 enabled_bit;
+	u32 clock_query_irq;
+	u32 setup_ready_irq;
+	bool clock_on;
+	bool notified;
+	bool disabled;
+	struct mutex mutex;
+	struct notifier_block panic_notifier;
+};
+
+/**
+ * ipa_smp2p_notify() - use SMP2P to tell modem about IPA clock state
+ * @smp2p:	SMP2P information
+ *
+ * This is called either when the modem has requested it (by triggering
+ * the modem clock query IPA interrupt) or whenever the AP is shutting down
+ * (via a panic notifier).  It sets the two SMP2P state bits--one saying
+ * whether the IPA clock is running, and the other indicating the first bit
+ * is valid.
+ */
+static void ipa_smp2p_notify(struct ipa_smp2p *smp2p)
+{
+	u32 value;
+	u32 mask;
+
+	if (smp2p->notified)
+		return;
+
+	smp2p->clock_on = ipa_clock_get_additional(smp2p->ipa);
+
+	/* Signal whether the clock is enabled */
+	mask = BIT(smp2p->enabled_bit);
+	value = smp2p->clock_on ? mask : 0;
+	qcom_smem_state_update_bits(smp2p->enabled_state, mask, value);
+
+	/* Now indicate that the enabled flag is valid */
+	mask = BIT(smp2p->valid_bit);
+	value = mask;
+	qcom_smem_state_update_bits(smp2p->valid_state, mask, value);
+
+	smp2p->notified = true;
+}
+
+/* Threaded IRQ handler for modem "ipa-clock-query" SMP2P interrupt */
+static irqreturn_t ipa_smp2p_modem_clk_query_isr(int irq, void *dev_id)
+{
+	struct ipa_smp2p *smp2p = dev_id;
+
+	ipa_smp2p_notify(smp2p);
+
+	return IRQ_HANDLED;
+}
+
+static int ipa_smp2p_panic_notifier(struct notifier_block *nb,
+				    unsigned long action, void *data)
+{
+	struct ipa_smp2p *smp2p;
+
+	smp2p = container_of(nb, struct ipa_smp2p, panic_notifier);
+
+	ipa_smp2p_notify(smp2p);
+
+	if (smp2p->clock_on)
+		ipa_uc_panic_notifier(smp2p->ipa);
+
+	return NOTIFY_DONE;
+}
+
+static int ipa_smp2p_panic_notifier_register(struct ipa_smp2p *smp2p)
+{
+	/* IPA panic handler needs to run before modem shuts down */
+	smp2p->panic_notifier.notifier_call = ipa_smp2p_panic_notifier;
+	smp2p->panic_notifier.priority = INT_MAX;	/* Do it early */
+
+	return atomic_notifier_chain_register(&panic_notifier_list,
+					      &smp2p->panic_notifier);
+}
+
+static void ipa_smp2p_panic_notifier_unregister(struct ipa_smp2p *smp2p)
+{
+	atomic_notifier_chain_unregister(&panic_notifier_list,
+					 &smp2p->panic_notifier);
+}
+
+/* Threaded IRQ handler for modem "ipa-setup-ready" SMP2P interrupt */
+static irqreturn_t ipa_smp2p_modem_setup_ready_isr(int irq, void *dev_id)
+{
+	struct ipa_smp2p *smp2p = dev_id;
+
+	mutex_lock(&smp2p->mutex);
+
+	if (!smp2p->disabled) {
+		int ret;
+
+		ret = ipa_setup(smp2p->ipa);
+		if (ret)
+			dev_err(&smp2p->ipa->pdev->dev,
+				"error %d from ipa_setup()\n", ret);
+		smp2p->disabled = true;
+	}
+
+	mutex_unlock(&smp2p->mutex);
+
+	return IRQ_HANDLED;
+}
+
+/* Initialize SMP2P interrupts */
+static int ipa_smp2p_irq_init(struct ipa_smp2p *smp2p, const char *name,
+			      irq_handler_t handler)
+{
+	struct device *dev = &smp2p->ipa->pdev->dev;
+	unsigned int irq;
+	int ret;
+
+	ret = platform_get_irq_byname(smp2p->ipa->pdev, name);
+	if (ret <= 0) {
+		dev_err(dev, "DT error %d getting \"%s\" IRQ property\n",
+			ret, name);
+		return ret ? : -EINVAL;
+	}
+	irq = ret;
+
+	ret = request_threaded_irq(irq, NULL, handler, 0, name, smp2p);
+	if (ret) {
+		dev_err(dev, "error %d requesting \"%s\" IRQ\n", ret, name);
+		return ret;
+	}
+
+	return irq;
+}
+
+static void ipa_smp2p_irq_exit(struct ipa_smp2p *smp2p, u32 irq)
+{
+	free_irq(irq, smp2p);
+}
+
+/* Drop the clock reference if it was taken in ipa_smp2p_notify() */
+static void ipa_smp2p_clock_release(struct ipa *ipa)
+{
+	if (!ipa->smp2p->clock_on)
+		return;
+
+	ipa_clock_put(ipa);
+	ipa->smp2p->clock_on = false;
+}
+
+/* Initialize the IPA SMP2P subsystem */
+int ipa_smp2p_init(struct ipa *ipa, bool modem_init)
+{
+	struct qcom_smem_state *enabled_state;
+	struct device *dev = &ipa->pdev->dev;
+	struct qcom_smem_state *valid_state;
+	struct ipa_smp2p *smp2p;
+	u32 enabled_bit;
+	u32 valid_bit;
+	int ret;
+
+	valid_state = qcom_smem_state_get(dev, "ipa-clock-enabled-valid",
+					  &valid_bit);
+	if (IS_ERR(valid_state))
+		return PTR_ERR(valid_state);
+	if (valid_bit >= 32)		/* BITS_PER_U32 */
+		return -EINVAL;
+
+	enabled_state = qcom_smem_state_get(dev, "ipa-clock-enabled",
+					    &enabled_bit);
+	if (IS_ERR(enabled_state))
+		return PTR_ERR(enabled_state);
+	if (enabled_bit >= 32)		/* BITS_PER_U32 */
+		return -EINVAL;
+
+	smp2p = kzalloc(sizeof(*smp2p), GFP_KERNEL);
+	if (!smp2p)
+		return -ENOMEM;
+
+	smp2p->ipa = ipa;
+
+	/* These fields are needed by the clock query interrupt
+	 * handler, so initialize them now.
+	 */
+	mutex_init(&smp2p->mutex);
+	smp2p->valid_state = valid_state;
+	smp2p->valid_bit = valid_bit;
+	smp2p->enabled_state = enabled_state;
+	smp2p->enabled_bit = enabled_bit;
+
+	/* We have enough information saved to handle notifications */
+	ipa->smp2p = smp2p;
+
+	ret = ipa_smp2p_irq_init(smp2p, "ipa-clock-query",
+				 ipa_smp2p_modem_clk_query_isr);
+	if (ret < 0)
+		goto err_null_smp2p;
+	smp2p->clock_query_irq = ret;
+
+	ret = ipa_smp2p_panic_notifier_register(smp2p);
+	if (ret)
+		goto err_irq_exit;
+
+	if (modem_init) {
+		/* Result will be non-zero (negative for error) */
+		ret = ipa_smp2p_irq_init(smp2p, "ipa-setup-ready",
+					 ipa_smp2p_modem_setup_ready_isr);
+		if (ret < 0)
+			goto err_notifier_unregister;
+		smp2p->setup_ready_irq = ret;
+	}
+
+	return 0;
+
+err_notifier_unregister:
+	ipa_smp2p_panic_notifier_unregister(smp2p);
+err_irq_exit:
+	ipa_smp2p_irq_exit(smp2p, smp2p->clock_query_irq);
+err_null_smp2p:
+	ipa->smp2p = NULL;
+	mutex_destroy(&smp2p->mutex);
+	kfree(smp2p);
+
+	return ret;
+}
+
+void ipa_smp2p_exit(struct ipa *ipa)
+{
+	struct ipa_smp2p *smp2p = ipa->smp2p;
+
+	if (smp2p->setup_ready_irq)
+		ipa_smp2p_irq_exit(smp2p, smp2p->setup_ready_irq);
+	ipa_smp2p_panic_notifier_unregister(smp2p);
+	ipa_smp2p_irq_exit(smp2p, smp2p->clock_query_irq);
+	/* We won't get notified any more; drop clock reference (if any) */
+	ipa_smp2p_clock_release(ipa);
+	ipa->smp2p = NULL;
+	mutex_destroy(&smp2p->mutex);
+	kfree(smp2p);
+}
+
+void ipa_smp2p_disable(struct ipa *ipa)
+{
+	struct ipa_smp2p *smp2p = ipa->smp2p;
+
+	if (!smp2p->setup_ready_irq)
+		return;
+
+	mutex_lock(&smp2p->mutex);
+
+	smp2p->disabled = true;
+
+	mutex_unlock(&smp2p->mutex);
+}
+
+/* Reset state tracking whether we have notified the modem */
+void ipa_smp2p_notify_reset(struct ipa *ipa)
+{
+	struct ipa_smp2p *smp2p = ipa->smp2p;
+	u32 mask;
+
+	if (!smp2p->notified)
+		return;
+
+	ipa_smp2p_clock_release(ipa);
+
+	/* Reset the clock enabled valid flag */
+	mask = BIT(smp2p->valid_bit);
+	qcom_smem_state_update_bits(smp2p->valid_state, mask, 0);
+
+	/* Mark the clock disabled for good measure... */
+	mask = BIT(smp2p->enabled_bit);
+	qcom_smem_state_update_bits(smp2p->enabled_state, mask, 0);
+
+	smp2p->notified = false;
+}