Hi Andre, > Subject: Re: [PATCH V6 2/2] mailbox: introduce ARM SMC based mailbox > > On Mon, 16 Sep 2019 09:44:41 +0000 > Peng Fan <peng.fan@xxxxxxx> wrote: > > Hi, > > looks quite good now, some smaller comments below. > I think the only thing left is the "function ID passed by the client" topic. > > Have you tried using this interface using hvc, for instance in KVM or Xen? For No. I do not have that implementation in hypervisor. > instance to provide access to a clock for a passed-through platform device? > Another use case that pops up from time to time is GPIO for guests. This > sounds like a use case for using the register interface, also we could use the > hvc return value. > > > 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://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore > > .kernel.org%2Fpatchwork%2Fpatch%2F812999%2F&data=02%7C01%7 > Cpeng.fa > > > n%40nxp.com%7C58a1ed4078264d14958f08d73b95ed7e%7C686ea1d3bc2b > 4c6fa92cd > > > 99c5c301635%7C0%7C1%7C637043387484474825&sdata=Cp1zlhlpQbg > BsWu9ZDV > > RKkXmd6kvUR%2BtPO7EPR7YLpA%3D&reserved=0 > > > > Cc: Andre Przywara <andre.przywara@xxxxxxx> > > Signed-off-by: Peng Fan <peng.fan@xxxxxxx> > > --- > > drivers/mailbox/Kconfig | 7 ++ > > drivers/mailbox/Makefile | 2 + > > drivers/mailbox/arm-smc-mailbox.c | 167 > > ++++++++++++++++++++++++++++++++++++++ > > 3 files changed, 176 insertions(+) > > create mode 100644 drivers/mailbox/arm-smc-mailbox.c > > > > diff --git a/drivers/mailbox/Kconfig b/drivers/mailbox/Kconfig index > > ab4eb750bbdd..7707ee26251a 100644 > > --- a/drivers/mailbox/Kconfig > > +++ b/drivers/mailbox/Kconfig > > @@ -16,6 +16,13 @@ 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..c84aef39c8d9 > > --- /dev/null > > +++ b/drivers/mailbox/arm-smc-mailbox.c > > @@ -0,0 +1,167 @@ > > +// 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/module.h> > > +#include <linux/platform_device.h> > > + > > +struct arm_smc_chan_data { > > + unsigned int function_id; > > +}; > > + > > +struct arm_smccc_mbox_cmd { > > + unsigned int function_id; > > + union { > > + unsigned int args_smccc32[6]; > > + unsigned long args_smccc64[6]; > > Shouldn't this be u32 and u64 here, as the data type has this explicit length in > the SMCCC? ok > > > + }; > > +}; > > If this is the data structure that this mailbox controller uses, I would expect > this to be documented somewhere, or even exported. Export this structure in include/linux/mailbox/smc-mailbox.h? > > And again, I don't like the idea of having the function ID in here. You mean function_id in arm_smccc_mbox_cmd is not good? > > > + > > +typedef unsigned long (smc_mbox_fn)(unsigned int, unsigned long, > > + unsigned long, unsigned long, > > + unsigned long, unsigned long, > > + unsigned long); > > +static smc_mbox_fn *invoke_smc_mbox_fn; > > + > > +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; > > + unsigned long ret; > > + u32 function_id; > > + > > + function_id = chan_data->function_id; > > + if (!function_id) > > + function_id = cmd->function_id; > > + > > + if (function_id & BIT(30)) { > > if (ARM_SMCCC_IS_64(function_id)) { ok > > > + ret = invoke_smc_mbox_fn(function_id, cmd->args_smccc64[0], > > + cmd->args_smccc64[1], > > + cmd->args_smccc64[2], > > + cmd->args_smccc64[3], > > + cmd->args_smccc64[4], > > + cmd->args_smccc64[5]); > > + } else { > > + ret = invoke_smc_mbox_fn(function_id, cmd->args_smccc32[0], > > + cmd->args_smccc32[1], > > + cmd->args_smccc32[2], > > + cmd->args_smccc32[3], > > + cmd->args_smccc32[4], > > + cmd->args_smccc32[5]); > > + } > > + > > + mbox_chan_received_data(link, (void *)ret); > > + > > + return 0; > > +} > > + > > +static unsigned long __invoke_fn_hvc(unsigned int function_id, > > + unsigned long arg0, unsigned long arg1, > > + unsigned long arg2, unsigned long arg3, > > + unsigned long arg4, unsigned long arg5) { > > + struct arm_smccc_res res; > > + > > + arm_smccc_hvc(function_id, arg0, arg1, arg2, arg3, arg4, > > + arg5, 0, &res); > > + return res.a0; > > +} > > + > > +static unsigned long __invoke_fn_smc(unsigned int function_id, > > + unsigned long arg0, unsigned long arg1, > > + unsigned long arg2, unsigned long arg3, > > + unsigned long arg4, unsigned long arg5) { > > + struct arm_smccc_res res; > > + > > + arm_smccc_smc(function_id, arg0, arg1, arg2, arg3, arg4, > > + arg5, 0, &res); > > + return res.a0; > > +} > > + > > +static const struct mbox_chan_ops arm_smc_mbox_chan_ops = { > > + .send_data = arm_smc_send_data, > > +}; > > + > > +static int arm_smc_mbox_probe(struct platform_device *pdev) { > > + struct device *dev = &pdev->dev; > > + struct mbox_controller *mbox; > > + struct arm_smc_chan_data *chan_data; > > + int ret; > > + u32 function_id = 0; > > + > > + if (of_device_is_compatible(dev->of_node, "arm,smc-mbox")) > > + invoke_smc_mbox_fn = __invoke_fn_smc; > > + else > > + invoke_smc_mbox_fn = __invoke_fn_hvc; > > + > > + mbox = devm_kzalloc(dev, sizeof(*mbox), GFP_KERNEL); > > + if (!mbox) > > + return -ENOMEM; > > + > > + mbox->num_chans = 1; > > + mbox->chans = devm_kzalloc(dev, sizeof(*mbox->chans), GFP_KERNEL); > > + if (!mbox->chans) > > + return -ENOMEM; > > + > > + chan_data = devm_kzalloc(dev, sizeof(*chan_data), GFP_KERNEL); > > + if (!chan_data) > > + return -ENOMEM; > > + > > + of_property_read_u32(dev->of_node, "arm,func-id", &function_id); > > + chan_data->function_id = function_id; > > + > > + mbox->chans->con_priv = chan_data; > > + > > + mbox->txdone_poll = false; > > + mbox->txdone_irq = false; > > Don't we need to provide something to confirm reception to the client? In our > case we can set this as soon as the smc/hvc returns. As smc/hvc returns, it means the transfer is over and receive is done. Thanks, Peng. > > Cheers, > Andre. > > > + mbox->ops = &arm_smc_mbox_chan_ops; > > + mbox->dev = dev; > > + > > + platform_set_drvdata(pdev, mbox); > > + > > + ret = devm_mbox_controller_register(dev, mbox); > > + if (ret) > > + return ret; > > + > > + dev_info(dev, "ARM SMC mailbox enabled.\n"); > > + > > + return ret; > > +} > > + > > +static int arm_smc_mbox_remove(struct platform_device *pdev) { > > + struct mbox_controller *mbox = platform_get_drvdata(pdev); > > + > > + mbox_controller_unregister(mbox); > > + return 0; > > +} > > + > > +static const struct of_device_id arm_smc_mbox_of_match[] = { > > + { .compatible = "arm,smc-mbox", }, > > + { .compatible = "arm,hvc-mbox", }, > > + {}, > > +}; > > +MODULE_DEVICE_TABLE(of, arm_smc_mbox_of_match); > > + > > +static struct platform_driver arm_smc_mbox_driver = { > > + .driver = { > > + .name = "arm-smc-mbox", > > + .of_match_table = arm_smc_mbox_of_match, > > + }, > > + .probe = arm_smc_mbox_probe, > > + .remove = arm_smc_mbox_remove, > > +}; > > +module_platform_driver(arm_smc_mbox_driver); > > + > > +MODULE_AUTHOR("Peng Fan <peng.fan@xxxxxxx>"); > > +MODULE_DESCRIPTION("Generic ARM smc mailbox driver"); > > +MODULE_LICENSE("GPL v2");
