From 0d58d8cfb6f989f290d983552fcaa116e582e84a Mon Sep 17 00:00:00 2001 From: Phil Elwell Date: Thu, 31 Oct 2024 17:33:38 +0000 Subject: [PATCH] mailbox: Add RP1 mailbox support The Raspberry Pi RP1 includes 2 M3 cores running firmware. This driver adds a mailbox communication channel to them via a doorbell and some shared memory. Signed-off-by: Phil Elwell --- drivers/mailbox/Kconfig | 9 ++ drivers/mailbox/Makefile | 2 + drivers/mailbox/rp1-mailbox.c | 208 ++++++++++++++++++++++++++++++++++ 3 files changed, 219 insertions(+) create mode 100644 drivers/mailbox/rp1-mailbox.c --- a/drivers/mailbox/Kconfig +++ b/drivers/mailbox/Kconfig @@ -295,4 +295,13 @@ config QCOM_IPCC acts as an interrupt controller for receiving interrupts from clients. Say Y here if you want to build this driver. +config MBOX_RP1 + tristate "RP1 Mailbox" + depends on MFD_RP1 + help + An implementation of a mailbox interface to the Raspberry Pi RP1 I/O + interface. Although written as a mailbox driver, the hardware only + provides an array of 32 doorbells. + Say Y here if you want to use the RP1 Mailbox. + endif --- a/drivers/mailbox/Makefile +++ b/drivers/mailbox/Makefile @@ -62,3 +62,5 @@ obj-$(CONFIG_SPRD_MBOX) += sprd-mailbox obj-$(CONFIG_QCOM_IPCC) += qcom-ipcc.o obj-$(CONFIG_APPLE_MAILBOX) += apple-mailbox.o + +obj-$(CONFIG_MBOX_RP1) += rp1-mailbox.o --- /dev/null +++ b/drivers/mailbox/rp1-mailbox.c @@ -0,0 +1,208 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2023 Raspberry Pi Ltd. + * + * Parts of this driver are based on: + * - bcm2835-mailbox.c + * Copyright (C) 2010,2015 Broadcom + * Copyright (C) 2013-2014 Lubomir Rintel + * Copyright (C) 2013 Craig McGeachie + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +/* + * RP1's PROC_EVENTS register can generate interrupts on the M3 cores (when + * enabled). The 32-bit register is treated as 32 events, all of which share a + * common interrupt. HOST_EVENTS is the same in the reverse direction. + */ +#define SYSCFG_PROC_EVENTS 0x00000008 +#define SYSCFG_HOST_EVENTS 0x0000000c +#define SYSCFG_HOST_EVENT_IRQ_EN 0x00000010 +#define SYSCFG_HOST_EVENT_IRQ 0x00000014 + +#define HW_SET_BITS 0x00002000 +#define HW_CLR_BITS 0x00003000 + +#define MAX_CHANS 4 /* 32 is the hardware limit */ + +struct rp1_mbox { + void __iomem *regs; + unsigned int irq; + struct mbox_controller controller; +}; + +static struct rp1_mbox *rp1_chan_mbox(struct mbox_chan *chan) +{ + return container_of(chan->mbox, struct rp1_mbox, controller); +} + +static unsigned int rp1_chan_event(struct mbox_chan *chan) +{ + return (unsigned int)(uintptr_t)chan->con_priv; +} + +static irqreturn_t rp1_mbox_irq(int irq, void *dev_id) +{ + struct rp1_mbox *mbox = dev_id; + struct mbox_chan *chan; + unsigned int doorbell; + unsigned int evs; + + evs = readl(mbox->regs + SYSCFG_HOST_EVENT_IRQ); + writel(evs, mbox->regs + SYSCFG_HOST_EVENTS + HW_CLR_BITS); + + while (evs) { + doorbell = __ffs(evs); + chan = &mbox->controller.chans[doorbell]; + mbox_chan_received_data(chan, NULL); + evs &= ~(1 << doorbell); + } + return IRQ_HANDLED; +} + +static int rp1_send_data(struct mbox_chan *chan, void *data) +{ + struct rp1_mbox *mbox = rp1_chan_mbox(chan); + unsigned int event = rp1_chan_event(chan); + + writel(event, mbox->regs + SYSCFG_PROC_EVENTS + HW_SET_BITS); + + return 0; +} + +static int rp1_startup(struct mbox_chan *chan) +{ + struct rp1_mbox *mbox = rp1_chan_mbox(chan); + unsigned int event = rp1_chan_event(chan); + + writel(event, mbox->regs + SYSCFG_HOST_EVENT_IRQ_EN + HW_SET_BITS); + + return 0; +} + +static void rp1_shutdown(struct mbox_chan *chan) +{ + struct rp1_mbox *mbox = rp1_chan_mbox(chan); + unsigned int event = rp1_chan_event(chan); + + writel(event, mbox->regs + SYSCFG_HOST_EVENT_IRQ_EN + HW_CLR_BITS); +} + +static bool rp1_last_tx_done(struct mbox_chan *chan) +{ + struct rp1_mbox *mbox = rp1_chan_mbox(chan); + unsigned int event = rp1_chan_event(chan); + unsigned int evs; + + evs = readl(mbox->regs + SYSCFG_HOST_EVENT_IRQ); + + return !(evs & event); +} + +static const struct mbox_chan_ops rp1_mbox_chan_ops = { + .send_data = rp1_send_data, + .startup = rp1_startup, + .shutdown = rp1_shutdown, + .last_tx_done = rp1_last_tx_done +}; + +static struct mbox_chan *rp1_mbox_xlate(struct mbox_controller *mbox, + const struct of_phandle_args *spec) +{ + struct mbox_chan *chan; + unsigned int doorbell; + + if (spec->args_count != 1) + return ERR_PTR(-EINVAL); + + doorbell = spec->args[0]; + if (doorbell >= MAX_CHANS) + return ERR_PTR(-EINVAL); + + chan = &mbox->chans[doorbell]; + if (chan->con_priv) + return ERR_PTR(-EBUSY); + + chan->con_priv = (void *)(uintptr_t)(1 << doorbell); + + return chan; +} + +static int rp1_mbox_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct mbox_chan *chans; + struct rp1_mbox *mbox; + int ret = 0; + + mbox = devm_kzalloc(dev, sizeof(*mbox), GFP_KERNEL); + if (mbox == NULL) + return -ENOMEM; + + ret = devm_request_irq(dev, platform_get_irq(pdev, 0), + rp1_mbox_irq, 0, dev_name(dev), mbox); + if (ret) { + dev_err(dev, "Failed to register a mailbox IRQ handler: %d\n", + ret); + return -ENODEV; + } + + mbox->regs = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(mbox->regs)) { + ret = PTR_ERR(mbox->regs); + return ret; + } + + chans = devm_kcalloc(dev, MAX_CHANS, sizeof(*chans), GFP_KERNEL); + if (!chans) + return -ENOMEM; + + mbox->controller.txdone_poll = true; + mbox->controller.txpoll_period = 5; + mbox->controller.ops = &rp1_mbox_chan_ops; + mbox->controller.of_xlate = &rp1_mbox_xlate; + mbox->controller.dev = dev; + mbox->controller.num_chans = MAX_CHANS; + mbox->controller.chans = chans; + + ret = devm_mbox_controller_register(dev, &mbox->controller); + if (ret) + return ret; + + platform_set_drvdata(pdev, mbox); + + return 0; +} + +static const struct of_device_id rp1_mbox_of_match[] = { + { .compatible = "raspberrypi,rp1-mbox", }, + {}, +}; +MODULE_DEVICE_TABLE(of, rp1_mbox_of_match); + +static struct platform_driver rp1_mbox_driver = { + .driver = { + .name = "rp1-mbox", + .of_match_table = rp1_mbox_of_match, + }, + .probe = rp1_mbox_probe, +}; + +module_platform_driver(rp1_mbox_driver); + +MODULE_AUTHOR("Phil Elwell "); +MODULE_DESCRIPTION("RP1 mailbox IPC driver"); +MODULE_LICENSE("GPL v2");