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kernel/drivers/mailbox/apple-mailbox.c
Hector Martin 68584e380e mailbox: apple: Implement poll_data() operation 
This allows clients running in atomic context to poll for messages to
arrive.

Signed-off-by: Hector Martin <marcan@marcan.st>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>
2022-09-15 13:14:01 -05:00

441 lines
12 KiB
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// SPDX-License-Identifier: GPL-2.0-only OR MIT
/*
* Apple mailbox driver
*
* Copyright (C) 2021 The Asahi Linux Contributors
*
* This driver adds support for two mailbox variants (called ASC and M3 by
* Apple) found in Apple SoCs such as the M1. It consists of two FIFOs used to
* exchange 64+32 bit messages between the main CPU and a co-processor.
* Various coprocessors implement different IPC protocols based on these simple
* messages and shared memory buffers.
*
* Both the main CPU and the co-processor see the same set of registers but
* the first FIFO (A2I) is always used to transfer messages from the application
* processor (us) to the I/O processor and the second one (I2A) for the
* other direction.
*/
#include <linux/apple-mailbox.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/gfp.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/mailbox_controller.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/spinlock.h>
#include <linux/types.h>
#define APPLE_ASC_MBOX_CONTROL_FULL BIT(16)
#define APPLE_ASC_MBOX_CONTROL_EMPTY BIT(17)
#define APPLE_ASC_MBOX_A2I_CONTROL 0x110
#define APPLE_ASC_MBOX_A2I_SEND0 0x800
#define APPLE_ASC_MBOX_A2I_SEND1 0x808
#define APPLE_ASC_MBOX_A2I_RECV0 0x810
#define APPLE_ASC_MBOX_A2I_RECV1 0x818
#define APPLE_ASC_MBOX_I2A_CONTROL 0x114
#define APPLE_ASC_MBOX_I2A_SEND0 0x820
#define APPLE_ASC_MBOX_I2A_SEND1 0x828
#define APPLE_ASC_MBOX_I2A_RECV0 0x830
#define APPLE_ASC_MBOX_I2A_RECV1 0x838
#define APPLE_M3_MBOX_CONTROL_FULL BIT(16)
#define APPLE_M3_MBOX_CONTROL_EMPTY BIT(17)
#define APPLE_M3_MBOX_A2I_CONTROL 0x50
#define APPLE_M3_MBOX_A2I_SEND0 0x60
#define APPLE_M3_MBOX_A2I_SEND1 0x68
#define APPLE_M3_MBOX_A2I_RECV0 0x70
#define APPLE_M3_MBOX_A2I_RECV1 0x78
#define APPLE_M3_MBOX_I2A_CONTROL 0x80
#define APPLE_M3_MBOX_I2A_SEND0 0x90
#define APPLE_M3_MBOX_I2A_SEND1 0x98
#define APPLE_M3_MBOX_I2A_RECV0 0xa0
#define APPLE_M3_MBOX_I2A_RECV1 0xa8
#define APPLE_M3_MBOX_IRQ_ENABLE 0x48
#define APPLE_M3_MBOX_IRQ_ACK 0x4c
#define APPLE_M3_MBOX_IRQ_A2I_EMPTY BIT(0)
#define APPLE_M3_MBOX_IRQ_A2I_NOT_EMPTY BIT(1)
#define APPLE_M3_MBOX_IRQ_I2A_EMPTY BIT(2)
#define APPLE_M3_MBOX_IRQ_I2A_NOT_EMPTY BIT(3)
#define APPLE_MBOX_MSG1_OUTCNT GENMASK(56, 52)
#define APPLE_MBOX_MSG1_INCNT GENMASK(51, 48)
#define APPLE_MBOX_MSG1_OUTPTR GENMASK(47, 44)
#define APPLE_MBOX_MSG1_INPTR GENMASK(43, 40)
#define APPLE_MBOX_MSG1_MSG GENMASK(31, 0)
struct apple_mbox_hw {
unsigned int control_full;
unsigned int control_empty;
unsigned int a2i_control;
unsigned int a2i_send0;
unsigned int a2i_send1;
unsigned int i2a_control;
unsigned int i2a_recv0;
unsigned int i2a_recv1;
bool has_irq_controls;
unsigned int irq_enable;
unsigned int irq_ack;
unsigned int irq_bit_recv_not_empty;
unsigned int irq_bit_send_empty;
};
struct apple_mbox {
void __iomem *regs;
const struct apple_mbox_hw *hw;
int irq_recv_not_empty;
int irq_send_empty;
struct mbox_chan chan;
struct device *dev;
struct mbox_controller controller;
spinlock_t rx_lock;
};
static const struct of_device_id apple_mbox_of_match[];
static bool apple_mbox_hw_can_send(struct apple_mbox *apple_mbox)
{
u32 mbox_ctrl =
readl_relaxed(apple_mbox->regs + apple_mbox->hw->a2i_control);
return !(mbox_ctrl & apple_mbox->hw->control_full);
}
static bool apple_mbox_hw_send_empty(struct apple_mbox *apple_mbox)
{
u32 mbox_ctrl =
readl_relaxed(apple_mbox->regs + apple_mbox->hw->a2i_control);
return mbox_ctrl & apple_mbox->hw->control_empty;
}
static int apple_mbox_hw_send(struct apple_mbox *apple_mbox,
struct apple_mbox_msg *msg)
{
if (!apple_mbox_hw_can_send(apple_mbox))
return -EBUSY;
dev_dbg(apple_mbox->dev, "> TX %016llx %08x\n", msg->msg0, msg->msg1);
writeq_relaxed(msg->msg0, apple_mbox->regs + apple_mbox->hw->a2i_send0);
writeq_relaxed(FIELD_PREP(APPLE_MBOX_MSG1_MSG, msg->msg1),
apple_mbox->regs + apple_mbox->hw->a2i_send1);
return 0;
}
static bool apple_mbox_hw_can_recv(struct apple_mbox *apple_mbox)
{
u32 mbox_ctrl =
readl_relaxed(apple_mbox->regs + apple_mbox->hw->i2a_control);
return !(mbox_ctrl & apple_mbox->hw->control_empty);
}
static int apple_mbox_hw_recv(struct apple_mbox *apple_mbox,
struct apple_mbox_msg *msg)
{
if (!apple_mbox_hw_can_recv(apple_mbox))
return -ENOMSG;
msg->msg0 = readq_relaxed(apple_mbox->regs + apple_mbox->hw->i2a_recv0);
msg->msg1 = FIELD_GET(
APPLE_MBOX_MSG1_MSG,
readq_relaxed(apple_mbox->regs + apple_mbox->hw->i2a_recv1));
dev_dbg(apple_mbox->dev, "< RX %016llx %08x\n", msg->msg0, msg->msg1);
return 0;
}
static int apple_mbox_chan_send_data(struct mbox_chan *chan, void *data)
{
struct apple_mbox *apple_mbox = chan->con_priv;
struct apple_mbox_msg *msg = data;
int ret;
ret = apple_mbox_hw_send(apple_mbox, msg);
if (ret)
return ret;
/*
* The interrupt is level triggered and will keep firing as long as the
* FIFO is empty. It will also keep firing if the FIFO was empty
* at any point in the past until it has been acknowledged at the
* mailbox level. By acknowledging it here we can ensure that we will
* only get the interrupt once the FIFO has been cleared again.
* If the FIFO is already empty before the ack it will fire again
* immediately after the ack.
*/
if (apple_mbox->hw->has_irq_controls) {
writel_relaxed(apple_mbox->hw->irq_bit_send_empty,
apple_mbox->regs + apple_mbox->hw->irq_ack);
}
enable_irq(apple_mbox->irq_send_empty);
return 0;
}
static irqreturn_t apple_mbox_send_empty_irq(int irq, void *data)
{
struct apple_mbox *apple_mbox = data;
/*
* We don't need to acknowledge the interrupt at the mailbox level
* here even if supported by the hardware. It will keep firing but that
* doesn't matter since it's disabled at the main interrupt controller.
* apple_mbox_chan_send_data will acknowledge it before enabling
* it at the main controller again.
*/
disable_irq_nosync(apple_mbox->irq_send_empty);
mbox_chan_txdone(&apple_mbox->chan, 0);
return IRQ_HANDLED;
}
static int apple_mbox_poll(struct apple_mbox *apple_mbox)
{
struct apple_mbox_msg msg;
int ret = 0;
while (apple_mbox_hw_recv(apple_mbox, &msg) == 0) {
mbox_chan_received_data(&apple_mbox->chan, (void *)&msg);
ret++;
}
/*
* The interrupt will keep firing even if there are no more messages
* unless we also acknowledge it at the mailbox level here.
* There's no race if a message comes in between the check in the while
* loop above and the ack below: If a new messages arrives inbetween
* those two the interrupt will just fire again immediately after the
* ack since it's level triggered.
*/
if (apple_mbox->hw->has_irq_controls) {
writel_relaxed(apple_mbox->hw->irq_bit_recv_not_empty,
apple_mbox->regs + apple_mbox->hw->irq_ack);
}
return ret;
}
static irqreturn_t apple_mbox_recv_irq(int irq, void *data)
{
struct apple_mbox *apple_mbox = data;
spin_lock(&apple_mbox->rx_lock);
apple_mbox_poll(apple_mbox);
spin_unlock(&apple_mbox->rx_lock);
return IRQ_HANDLED;
}
static bool apple_mbox_chan_peek_data(struct mbox_chan *chan)
{
struct apple_mbox *apple_mbox = chan->con_priv;
unsigned long flags;
int ret;
spin_lock_irqsave(&apple_mbox->rx_lock, flags);
ret = apple_mbox_poll(apple_mbox);
spin_unlock_irqrestore(&apple_mbox->rx_lock, flags);
return ret > 0;
}
static int apple_mbox_chan_flush(struct mbox_chan *chan, unsigned long timeout)
{
struct apple_mbox *apple_mbox = chan->con_priv;
unsigned long deadline = jiffies + msecs_to_jiffies(timeout);
while (time_before(jiffies, deadline)) {
if (apple_mbox_hw_send_empty(apple_mbox)) {
mbox_chan_txdone(&apple_mbox->chan, 0);
return 0;
}
udelay(1);
}
return -ETIME;
}
static int apple_mbox_chan_startup(struct mbox_chan *chan)
{
struct apple_mbox *apple_mbox = chan->con_priv;
/*
* Only some variants of this mailbox HW provide interrupt control
* at the mailbox level. We therefore need to handle enabling/disabling
* interrupts at the main interrupt controller anyway for hardware that
* doesn't. Just always keep the interrupts we care about enabled at
* the mailbox level so that both hardware revisions behave almost
* the same.
*/
if (apple_mbox->hw->has_irq_controls) {
writel_relaxed(apple_mbox->hw->irq_bit_recv_not_empty |
apple_mbox->hw->irq_bit_send_empty,
apple_mbox->regs + apple_mbox->hw->irq_enable);
}
enable_irq(apple_mbox->irq_recv_not_empty);
return 0;
}
static void apple_mbox_chan_shutdown(struct mbox_chan *chan)
{
struct apple_mbox *apple_mbox = chan->con_priv;
disable_irq(apple_mbox->irq_recv_not_empty);
}
static const struct mbox_chan_ops apple_mbox_ops = {
.send_data = apple_mbox_chan_send_data,
.peek_data = apple_mbox_chan_peek_data,
.flush = apple_mbox_chan_flush,
.startup = apple_mbox_chan_startup,
.shutdown = apple_mbox_chan_shutdown,
};
static struct mbox_chan *apple_mbox_of_xlate(struct mbox_controller *mbox,
const struct of_phandle_args *args)
{
if (args->args_count != 0)
return ERR_PTR(-EINVAL);
return &mbox->chans[0];
}
static int apple_mbox_probe(struct platform_device *pdev)
{
int ret;
const struct of_device_id *match;
char *irqname;
struct apple_mbox *mbox;
struct device *dev = &pdev->dev;
match = of_match_node(apple_mbox_of_match, pdev->dev.of_node);
if (!match)
return -EINVAL;
if (!match->data)
return -EINVAL;
mbox = devm_kzalloc(dev, sizeof(*mbox), GFP_KERNEL);
if (!mbox)
return -ENOMEM;
platform_set_drvdata(pdev, mbox);
mbox->dev = dev;
mbox->regs = devm_platform_ioremap_resource(pdev, 0);
if (IS_ERR(mbox->regs))
return PTR_ERR(mbox->regs);
mbox->hw = match->data;
mbox->irq_recv_not_empty =
platform_get_irq_byname(pdev, "recv-not-empty");
if (mbox->irq_recv_not_empty < 0)
return -ENODEV;
mbox->irq_send_empty = platform_get_irq_byname(pdev, "send-empty");
if (mbox->irq_send_empty < 0)
return -ENODEV;
mbox->controller.dev = mbox->dev;
mbox->controller.num_chans = 1;
mbox->controller.chans = &mbox->chan;
mbox->controller.ops = &apple_mbox_ops;
mbox->controller.txdone_irq = true;
mbox->controller.of_xlate = apple_mbox_of_xlate;
mbox->chan.con_priv = mbox;
spin_lock_init(&mbox->rx_lock);
irqname = devm_kasprintf(dev, GFP_KERNEL, "%s-recv", dev_name(dev));
if (!irqname)
return -ENOMEM;
ret = devm_request_threaded_irq(dev, mbox->irq_recv_not_empty, NULL,
apple_mbox_recv_irq,
IRQF_NO_AUTOEN | IRQF_ONESHOT, irqname,
mbox);
if (ret)
return ret;
irqname = devm_kasprintf(dev, GFP_KERNEL, "%s-send", dev_name(dev));
if (!irqname)
return -ENOMEM;
ret = devm_request_irq(dev, mbox->irq_send_empty,
apple_mbox_send_empty_irq, IRQF_NO_AUTOEN,
irqname, mbox);
if (ret)
return ret;
return devm_mbox_controller_register(dev, &mbox->controller);
}
static const struct apple_mbox_hw apple_mbox_asc_hw = {
.control_full = APPLE_ASC_MBOX_CONTROL_FULL,
.control_empty = APPLE_ASC_MBOX_CONTROL_EMPTY,
.a2i_control = APPLE_ASC_MBOX_A2I_CONTROL,
.a2i_send0 = APPLE_ASC_MBOX_A2I_SEND0,
.a2i_send1 = APPLE_ASC_MBOX_A2I_SEND1,
.i2a_control = APPLE_ASC_MBOX_I2A_CONTROL,
.i2a_recv0 = APPLE_ASC_MBOX_I2A_RECV0,
.i2a_recv1 = APPLE_ASC_MBOX_I2A_RECV1,
.has_irq_controls = false,
};
static const struct apple_mbox_hw apple_mbox_m3_hw = {
.control_full = APPLE_M3_MBOX_CONTROL_FULL,
.control_empty = APPLE_M3_MBOX_CONTROL_EMPTY,
.a2i_control = APPLE_M3_MBOX_A2I_CONTROL,
.a2i_send0 = APPLE_M3_MBOX_A2I_SEND0,
.a2i_send1 = APPLE_M3_MBOX_A2I_SEND1,
.i2a_control = APPLE_M3_MBOX_I2A_CONTROL,
.i2a_recv0 = APPLE_M3_MBOX_I2A_RECV0,
.i2a_recv1 = APPLE_M3_MBOX_I2A_RECV1,
.has_irq_controls = true,
.irq_enable = APPLE_M3_MBOX_IRQ_ENABLE,
.irq_ack = APPLE_M3_MBOX_IRQ_ACK,
.irq_bit_recv_not_empty = APPLE_M3_MBOX_IRQ_I2A_NOT_EMPTY,
.irq_bit_send_empty = APPLE_M3_MBOX_IRQ_A2I_EMPTY,
};
static const struct of_device_id apple_mbox_of_match[] = {
{ .compatible = "apple,asc-mailbox-v4", .data = &apple_mbox_asc_hw },
{ .compatible = "apple,m3-mailbox-v2", .data = &apple_mbox_m3_hw },
{}
};
MODULE_DEVICE_TABLE(of, apple_mbox_of_match);
static struct platform_driver apple_mbox_driver = {
.driver = {
.name = "apple-mailbox",
.of_match_table = apple_mbox_of_match,
},
.probe = apple_mbox_probe,
};
module_platform_driver(apple_mbox_driver);
MODULE_LICENSE("Dual MIT/GPL");
MODULE_AUTHOR("Sven Peter <sven@svenpeter.dev>");
MODULE_DESCRIPTION("Apple Mailbox driver");
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