On Mon, Jun 3, 2019 at 3:28 AM <peng.fan@xxxxxxx> wrote: > > From: Peng Fan <peng.fan@xxxxxxx> > > This mailbox driver implements a mailbox which signals transmitted data > via an ARM smc (secure monitor call) instruction. The mailbox receiver > is implemented in firmware and can synchronously return data when it > returns execution to the non-secure world again. > An asynchronous receive path is not implemented. > This allows the usage of a mailbox to trigger firmware actions on SoCs > which either don't have a separate management processor or on which such > a core is not available. A user of this mailbox could be the SCP > interface. > > Modified from Andre Przywara's v2 patch > https://lore.kernel.org/patchwork/patch/812999/ > > Cc: Andre Przywara <andre.przywara@xxxxxxx> > Signed-off-by: Peng Fan <peng.fan@xxxxxxx> > --- > > V2: > Add interrupts notification support. > > drivers/mailbox/Kconfig | 7 ++ > drivers/mailbox/Makefile | 2 + > drivers/mailbox/arm-smc-mailbox.c | 190 ++++++++++++++++++++++++++++++++ > include/linux/mailbox/arm-smc-mailbox.h | 10 ++ > 4 files changed, 209 insertions(+) > create mode 100644 drivers/mailbox/arm-smc-mailbox.c > create mode 100644 include/linux/mailbox/arm-smc-mailbox.h > > diff --git a/drivers/mailbox/Kconfig b/drivers/mailbox/Kconfig > index 595542bfae85..c3bd0f1ddcd8 100644 > --- a/drivers/mailbox/Kconfig > +++ b/drivers/mailbox/Kconfig > @@ -15,6 +15,13 @@ config ARM_MHU > The controller has 3 mailbox channels, the last of which can be > used in Secure mode only. > > +config ARM_SMC_MBOX > + tristate "Generic ARM smc mailbox" > + depends on OF && HAVE_ARM_SMCCC > + help > + Generic mailbox driver which uses ARM smc calls to call into > + firmware for triggering mailboxes. > + > config IMX_MBOX > tristate "i.MX Mailbox" > depends on ARCH_MXC || COMPILE_TEST > diff --git a/drivers/mailbox/Makefile b/drivers/mailbox/Makefile > index c22fad6f696b..93918a84c91b 100644 > --- a/drivers/mailbox/Makefile > +++ b/drivers/mailbox/Makefile > @@ -7,6 +7,8 @@ obj-$(CONFIG_MAILBOX_TEST) += mailbox-test.o > > obj-$(CONFIG_ARM_MHU) += arm_mhu.o > > +obj-$(CONFIG_ARM_SMC_MBOX) += arm-smc-mailbox.o > + > obj-$(CONFIG_IMX_MBOX) += imx-mailbox.o > > obj-$(CONFIG_ARMADA_37XX_RWTM_MBOX) += armada-37xx-rwtm-mailbox.o > diff --git a/drivers/mailbox/arm-smc-mailbox.c b/drivers/mailbox/arm-smc-mailbox.c > new file mode 100644 > index 000000000000..fef6e38d8b98 > --- /dev/null > +++ b/drivers/mailbox/arm-smc-mailbox.c > @@ -0,0 +1,190 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * Copyright (C) 2016,2017 ARM Ltd. > + * Copyright 2019 NXP > + */ > + > +#include <linux/arm-smccc.h> > +#include <linux/device.h> > +#include <linux/kernel.h> > +#include <linux/interrupt.h> > +#include <linux/mailbox_controller.h> > +#include <linux/mailbox/arm-smc-mailbox.h> > +#include <linux/module.h> > +#include <linux/platform_device.h> > + > +#define ARM_SMC_MBOX_USE_HVC BIT(0) > +#define ARM_SMC_MBOX_USB_IRQ BIT(1) > + IRQ bit is unused (and unnecessary IMO) > +struct arm_smc_chan_data { > + u32 function_id; > + u32 flags; > + int irq; > +}; > + > +static int arm_smc_send_data(struct mbox_chan *link, void *data) > +{ > + struct arm_smc_chan_data *chan_data = link->con_priv; > + struct arm_smccc_mbox_cmd *cmd = data; > + struct arm_smccc_res res; > + u32 function_id; > + > + if (chan_data->function_id != UINT_MAX) > + function_id = chan_data->function_id; > + else > + function_id = cmd->a0; > + Not sure about chan_data->function_id. Why restrict from DT? 'a0' is the function_id register, let the user pass func-id via the 'a0' like other values via 'a[1-7]' > + if (chan_data->flags & ARM_SMC_MBOX_USE_HVC) > + arm_smccc_hvc(function_id, cmd->a1, cmd->a2, cmd->a3, cmd->a4, > + cmd->a5, cmd->a6, cmd->a7, &res); > + else > + arm_smccc_smc(function_id, cmd->a1, cmd->a2, cmd->a3, cmd->a4, > + cmd->a5, cmd->a6, cmd->a7, &res); > + > + if (chan_data->irq) > + return 0; > + This irq thing seems like oob signalling, that is, a protocol thing. And then it provides lesser info via chan_irq_handler (returns NULL) than res.a0 - which can always be ignored if not needed. So the irq should be implemented in the upper layer if the protocol needs it. > + mbox_chan_received_data(link, (void *)res.a0); > + This is fine.
