// SPDX-License-Identifier: GPL-2.0 // // Copyright (c) 2017-2019 Samuel Holland <samuel@sholland.org> #include <linux/bitops.h> #include <linux/clk.h> #include <linux/device.h> #include <linux/err.h> #include <linux/interrupt.h> #include <linux/io.h> #include <linux/kernel.h> #include <linux/mailbox_controller.h> #include <linux/module.h> #include <linux/of.h> #include <linux/of_irq.h> #include <linux/platform_device.h> #include <linux/reset.h> #include <linux/spinlock.h> #define NUM_CHANS 8 #define CTRL_REG(n) (0x0000 + 0x4 * ((n) / 4)) #define CTRL_RX(n) BIT(0 + 8 * ((n) % 4)) #define CTRL_TX(n) BIT(4 + 8 * ((n) % 4)) #define REMOTE_IRQ_EN_REG 0x0040 #define REMOTE_IRQ_STAT_REG 0x0050 #define LOCAL_IRQ_EN_REG 0x0060 #define LOCAL_IRQ_STAT_REG 0x0070 #define RX_IRQ(n) BIT(0 + 2 * (n)) #define RX_IRQ_MASK 0x5555 #define TX_IRQ(n) BIT(1 + 2 * (n)) #define TX_IRQ_MASK 0xaaaa #define FIFO_STAT_REG(n) (0x0100 + 0x4 * (n)) #define FIFO_STAT_MASK GENMASK(0, 0) #define MSG_STAT_REG(n) (0x0140 + 0x4 * (n)) #define MSG_STAT_MASK GENMASK(2, 0) #define MSG_DATA_REG(n) (0x0180 + 0x4 * (n)) #define mbox_dbg(mbox, ...) dev_dbg((mbox)->controller.dev, __VA_ARGS__) struct sun6i_msgbox { struct mbox_controller controller; struct clk *clk; spinlock_t lock; void __iomem *regs; }; static bool sun6i_msgbox_last_tx_done(struct mbox_chan *chan); static bool sun6i_msgbox_peek_data(struct mbox_chan *chan); static inline int channel_number(struct mbox_chan *chan) { return chan - chan->mbox->chans; } static inline struct sun6i_msgbox *to_sun6i_msgbox(struct mbox_chan *chan) { return chan->con_priv; } static irqreturn_t sun6i_msgbox_irq(int irq, void *dev_id) { struct sun6i_msgbox *mbox = dev_id; uint32_t status; int n; /* Only examine channels that are currently enabled. */ status = readl(mbox->regs + LOCAL_IRQ_EN_REG) & readl(mbox->regs + LOCAL_IRQ_STAT_REG); if (!(status & RX_IRQ_MASK)) return IRQ_NONE; for (n = 0; n < NUM_CHANS; ++n) { struct mbox_chan *chan = &mbox->controller.chans[n]; if (!(status & RX_IRQ(n))) continue; while (sun6i_msgbox_peek_data(chan)) { uint32_t msg = readl(mbox->regs + MSG_DATA_REG(n)); mbox_dbg(mbox, "Channel %d received 0x%08x\n", n, msg); mbox_chan_received_data(chan, &msg); } /* The IRQ can be cleared only once the FIFO is empty. */ writel(RX_IRQ(n), mbox->regs + LOCAL_IRQ_STAT_REG); } return IRQ_HANDLED; } static int sun6i_msgbox_send_data(struct mbox_chan *chan, void *data) { struct sun6i_msgbox *mbox = to_sun6i_msgbox(chan); int n = channel_number(chan); uint32_t msg = *(uint32_t *)data; /* Using a channel backwards gets the hardware into a bad state. */ if (WARN_ON_ONCE(!(readl(mbox->regs + CTRL_REG(n)) & CTRL_TX(n)))) return 0; writel(msg, mbox->regs + MSG_DATA_REG(n)); mbox_dbg(mbox, "Channel %d sent 0x%08x\n", n, msg); return 0; } static int sun6i_msgbox_startup(struct mbox_chan *chan) { struct sun6i_msgbox *mbox = to_sun6i_msgbox(chan); int n = channel_number(chan); /* The coprocessor is responsible for setting channel directions. */ if (readl(mbox->regs + CTRL_REG(n)) & CTRL_RX(n)) { /* Flush the receive FIFO. */ while (sun6i_msgbox_peek_data(chan)) readl(mbox->regs + MSG_DATA_REG(n)); writel(RX_IRQ(n), mbox->regs + LOCAL_IRQ_STAT_REG); /* Enable the receive IRQ. */ spin_lock(&mbox->lock); writel(readl(mbox->regs + LOCAL_IRQ_EN_REG) | RX_IRQ(n), mbox->regs + LOCAL_IRQ_EN_REG); spin_unlock(&mbox->lock); } mbox_dbg(mbox, "Channel %d startup complete\n", n); return 0; } static void sun6i_msgbox_shutdown(struct mbox_chan *chan) { struct sun6i_msgbox *mbox = to_sun6i_msgbox(chan); int n = channel_number(chan); if (readl(mbox->regs + CTRL_REG(n)) & CTRL_RX(n)) { /* Disable the receive IRQ. */ spin_lock(&mbox->lock); writel(readl(mbox->regs + LOCAL_IRQ_EN_REG) & ~RX_IRQ(n), mbox->regs + LOCAL_IRQ_EN_REG); spin_unlock(&mbox->lock); /* Attempt to flush the FIFO until the IRQ is cleared. */ do { while (sun6i_msgbox_peek_data(chan)) readl(mbox->regs + MSG_DATA_REG(n)); writel(RX_IRQ(n), mbox->regs + LOCAL_IRQ_STAT_REG); } while (readl(mbox->regs + LOCAL_IRQ_STAT_REG) & RX_IRQ(n)); } mbox_dbg(mbox, "Channel %d shutdown complete\n", n); } static bool sun6i_msgbox_last_tx_done(struct mbox_chan *chan) { struct sun6i_msgbox *mbox = to_sun6i_msgbox(chan); int n = channel_number(chan); /* * The hardware allows snooping on the remote user's IRQ statuses. * We consider a message to be acknowledged only once the receive IRQ * for that channel is cleared. Since the receive IRQ for a channel * cannot be cleared until the FIFO for that channel is empty, this * ensures that the message has actually been read. It also gives the * recipient an opportunity to perform minimal processing before * acknowledging the message. */ return !(readl(mbox->regs + REMOTE_IRQ_STAT_REG) & RX_IRQ(n)); } static bool sun6i_msgbox_peek_data(struct mbox_chan *chan) { struct sun6i_msgbox *mbox = to_sun6i_msgbox(chan); int n = channel_number(chan); return readl(mbox->regs + MSG_STAT_REG(n)) & MSG_STAT_MASK; } static const struct mbox_chan_ops sun6i_msgbox_chan_ops = { .send_data = sun6i_msgbox_send_data, .startup = sun6i_msgbox_startup, .shutdown = sun6i_msgbox_shutdown, .last_tx_done = sun6i_msgbox_last_tx_done, .peek_data = sun6i_msgbox_peek_data, }; static int sun6i_msgbox_probe(struct platform_device *pdev) { struct device *dev = &pdev->dev; struct mbox_chan *chans; struct reset_control *reset; struct sun6i_msgbox *mbox; int i, ret; mbox = devm_kzalloc(dev, sizeof(*mbox), GFP_KERNEL); if (!mbox) return -ENOMEM; chans = devm_kcalloc(dev, NUM_CHANS, sizeof(*chans), GFP_KERNEL); if (!chans) return -ENOMEM; for (i = 0; i < NUM_CHANS; ++i) chans[i].con_priv = mbox; mbox->clk = devm_clk_get(dev, NULL); if (IS_ERR(mbox->clk)) { ret = PTR_ERR(mbox->clk); dev_err(dev, "Failed to get clock: %d\n", ret); return ret; } ret = clk_prepare_enable(mbox->clk); if (ret) { dev_err(dev, "Failed to enable clock: %d\n", ret); return ret; } reset = devm_reset_control_get_exclusive(dev, NULL); if (IS_ERR(reset)) { ret = PTR_ERR(reset); dev_err(dev, "Failed to get reset control: %d\n", ret); goto err_disable_unprepare; } /* * NOTE: We rely on platform firmware to preconfigure the channel * directions, and we share this hardware block with other firmware * that runs concurrently with Linux (e.g. a trusted monitor). * * Therefore, we do *not* assert the reset line if probing fails or * when removing the device. */ ret = reset_control_deassert(reset); if (ret) { dev_err(dev, "Failed to deassert reset: %d\n", ret); goto err_disable_unprepare; } mbox->regs = devm_platform_ioremap_resource(pdev, 0); if (IS_ERR(mbox->regs)) { ret = PTR_ERR(mbox->regs); dev_err(dev, "Failed to map MMIO resource: %d\n", ret); goto err_disable_unprepare; } /* Disable all IRQs for this end of the msgbox. */ writel(0, mbox->regs + LOCAL_IRQ_EN_REG); ret = devm_request_irq(dev, irq_of_parse_and_map(dev->of_node, 0), sun6i_msgbox_irq, 0, dev_name(dev), mbox); if (ret) { dev_err(dev, "Failed to register IRQ handler: %d\n", ret); goto err_disable_unprepare; } mbox->controller.dev = dev; mbox->controller.ops = &sun6i_msgbox_chan_ops; mbox->controller.chans = chans; mbox->controller.num_chans = NUM_CHANS; mbox->controller.txdone_irq = false; mbox->controller.txdone_poll = true; mbox->controller.txpoll_period = 5; spin_lock_init(&mbox->lock); platform_set_drvdata(pdev, mbox); ret = mbox_controller_register(&mbox->controller); if (ret) { dev_err(dev, "Failed to register controller: %d\n", ret); goto err_disable_unprepare; } return 0; err_disable_unprepare: clk_disable_unprepare(mbox->clk); return ret; } static int sun6i_msgbox_remove(struct platform_device *pdev) { struct sun6i_msgbox *mbox = platform_get_drvdata(pdev); mbox_controller_unregister(&mbox->controller); /* See the comment in sun6i_msgbox_probe about the reset line. */ clk_disable_unprepare(mbox->clk); return 0; } static const struct of_device_id sun6i_msgbox_of_match[] = { { .compatible = "allwinner,sun6i-a31-msgbox", }, {}, }; MODULE_DEVICE_TABLE(of, sun6i_msgbox_of_match); static struct platform_driver sun6i_msgbox_driver = { .driver = { .name = "sun6i-msgbox", .of_match_table = sun6i_msgbox_of_match, }, .probe = sun6i_msgbox_probe, .remove = sun6i_msgbox_remove, }; module_platform_driver(sun6i_msgbox_driver); MODULE_AUTHOR("Samuel Holland <samuel@sholland.org>"); MODULE_DESCRIPTION("Allwinner sun6i/sun8i/sun9i/sun50i Message Box"); MODULE_LICENSE("GPL v2");