On 6/3/19 1:30 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> > --- [snip] +#define ARM_SMC_MBOX_USB_IRQ BIT(1) That flag appears unused. > +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; > + const char *method; > + bool use_hvc = false; > + int ret, irq_count, i; > + u32 val; > + > + if (!of_property_read_u32(dev->of_node, "arm,num-chans", &val)) { > + if (val < 1 || val > INT_MAX) { > + dev_err(dev, "invalid arm,num-chans value %u of %pOFn\n", val, pdev->dev.of_node); > + return -EINVAL; > + } > + } Should not the upper bound check be done against UINT_MAX since val is an unsigned int? > + > + irq_count = platform_irq_count(pdev); > + if (irq_count == -EPROBE_DEFER) > + return irq_count; > + > + if (irq_count && irq_count != val) { > + dev_err(dev, "Interrupts not match num-chans\n"); Interrupts property does not match \"arm,num-chans\" would be more correct. > + return -EINVAL; > + } > + > + if (!of_property_read_string(dev->of_node, "method", &method)) { > + if (!strcmp("hvc", method)) { > + use_hvc = true; > + } else if (!strcmp("smc", method)) { > + use_hvc = false; > + } else { > + dev_warn(dev, "invalid \"method\" property: %s\n", > + method); > + > + return -EINVAL; > + } Having at least one method specified does not seem to be checked later on in the code, so if I omitted to specify that property, we would still register the mailbox and default to use "smc" since the ARM_SMC_MBOX_USE_HVC flag would not be set, would not we want to make sure that we do have in fact a valid method specified given the binding documents that property as mandatory? [snip] > + mbox->txdone_poll = false; > + mbox->txdone_irq = false; > + mbox->ops = &arm_smc_mbox_chan_ops; > + mbox->dev = dev; > + > + ret = mbox_controller_register(mbox); > + if (ret) > + return ret; > + > + platform_set_drvdata(pdev, mbox); I would move this above mbox_controller_register() that way there is no room for race conditions in case another part of the driver expects to have pdev->dev.drvdata set before the mbox controller is registered. Since you use devm_* functions for everything, you may even remove that call. [snip] > +#ifndef _LINUX_ARM_SMC_MAILBOX_H_ > +#define _LINUX_ARM_SMC_MAILBOX_H_ > + > +struct arm_smccc_mbox_cmd { > + unsigned long a0, a1, a2, a3, a4, a5, a6, a7; > +}; Do you expect this to be used by other in-kernel users? If so, it might be good to document how a0 can have a special meaning and be used as a substitute for the function_id? -- Florian
