On Thu, Nov 07, 2024 at 03:38:27PM -0800, Elliot Berman wrote: > SoC vendors have different types of resets and are controlled through > various registers. For instance, Qualcomm chipsets can reboot to a > "download mode" that allows a RAM dump to be collected. Another example > is they also support writing a cookie that can be read by bootloader > during next boot. PSCI offers a mechanism, SYSTEM_RESET2, for these > vendor reset types to be implemented without requiring drivers for every > register/cookie. > > Add support in PSCI to statically map reboot mode commands from > userspace to a vendor reset and cookie value using the device tree. > > A separate initcall is needed to parse the devicetree, instead of using > psci_dt_init because mm isn't sufficiently set up to allocate memory. Nit: information below this point is more a cover letter than for the commit log. > Reboot mode framework is close but doesn't quite fit with the > design and requirements for PSCI SYSTEM_RESET2. Some of these issues can > be solved but doesn't seem reasonable in sum: > 1. reboot mode registers against the reboot_notifier_list, which is too > early to call SYSTEM_RESET2. PSCI would need to remember the reset > type from the reboot-mode framework callback and use it > psci_sys_reset. > 2. reboot mode assumes only one cookie/parameter is described in the > device tree. SYSTEM_RESET2 uses 2: one for the type and one for > cookie. > 3. psci cpuidle driver already registers a driver against the > arm,psci-1.0 compatible. Refactoring would be needed to have both a > cpuidle and reboot-mode driver. > > Tested-by: Florian Fainelli <florian.fainelli@xxxxxxxxxxxx> > Signed-off-by: Elliot Berman <quic_eberman@xxxxxxxxxxx> > --- > drivers/firmware/psci/psci.c | 104 +++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 104 insertions(+) > > diff --git a/drivers/firmware/psci/psci.c b/drivers/firmware/psci/psci.c > index 2328ca58bba61fdb677ac20a1a7447882cd0cf22..e60e3f8749c5a6732c51d23a2c1f453361132d9a 100644 > --- a/drivers/firmware/psci/psci.c > +++ b/drivers/firmware/psci/psci.c > @@ -79,6 +79,14 @@ struct psci_0_1_function_ids get_psci_0_1_function_ids(void) > static u32 psci_cpu_suspend_feature; > static bool psci_system_reset2_supported; > > +struct psci_reset_param { > + const char *mode; > + u32 reset_type; > + u32 cookie; > +}; > +static struct psci_reset_param *psci_reset_params __ro_after_init; > +static size_t num_psci_reset_params __ro_after_init; > + > static inline bool psci_has_ext_power_state(void) > { > return psci_cpu_suspend_feature & > @@ -305,9 +313,38 @@ static int get_set_conduit_method(const struct device_node *np) > return 0; > } > > +static void psci_vendor_system_reset2(const char *cmd) > +{ > + unsigned long ret; > + size_t i; > + > + for (i = 0; i < num_psci_reset_params; i++) { > + if (!strcmp(psci_reset_params[i].mode, cmd)) { > + ret = invoke_psci_fn(PSCI_FN_NATIVE(1_1, SYSTEM_RESET2), > + psci_reset_params[i].reset_type, > + psci_reset_params[i].cookie, 0); > + /* > + * if vendor reset fails, log it and fall back to > + * architecture reset types > + */ > + pr_err("failed to perform reset \"%s\": %ld\n", cmd, > + (long)ret); > + return; > + } > + } > +} > + > static int psci_sys_reset(struct notifier_block *nb, unsigned long action, > void *data) > { > + /* > + * try to do the vendor system_reset2 > + * If the reset fails or there wasn't a match on the command, > + * fall back to architectural resets > + */ > + if (data && num_psci_reset_params) > + psci_vendor_system_reset2(data); > + > if ((reboot_mode == REBOOT_WARM || reboot_mode == REBOOT_SOFT) && > psci_system_reset2_supported) { This is a mess. To issue architectural warm reset we check reboot_mode, for vendor resets we ignore it - there is no rationale, that's the point I am making. Also see my question on the other thread re: user space and reset "modes". I appreciate we are not making progress but I don't want to pick up the pieces later after merging this code - it is unclear to me what's the best path forward - I would like to understand how other platforms/arches behave in this respect. > /* > @@ -750,6 +787,73 @@ static const struct of_device_id psci_of_match[] __initconst = { > {}, > }; > > +#define REBOOT_PREFIX "mode-" > + > +static int __init psci_init_system_reset2_modes(void) > +{ > + const size_t len = strlen(REBOOT_PREFIX); > + struct psci_reset_param *param; > + struct device_node *psci_np __free(device_node) = NULL; > + struct device_node *np __free(device_node) = NULL; > + struct property *prop; > + size_t count = 0; > + u32 magic[2]; > + int num; > + > + if (!psci_system_reset2_supported) > + return 0; > + > + psci_np = of_find_matching_node(NULL, psci_of_match); > + if (!psci_np) > + return 0; > + > + np = of_find_node_by_name(psci_np, "reset-types"); > + if (!np) > + return 0; > + > + for_each_property_of_node(np, prop) { > + if (strncmp(prop->name, REBOOT_PREFIX, len)) > + continue; > + num = of_property_count_u32_elems(np, prop->name); > + if (num != 1 && num != 2) > + continue; > + > + count++; > + } > + > + param = psci_reset_params = > + kcalloc(count, sizeof(*psci_reset_params), GFP_KERNEL); > + if (!psci_reset_params) > + return -ENOMEM; > + > + for_each_property_of_node(np, prop) { > + if (strncmp(prop->name, REBOOT_PREFIX, len)) > + continue; > + > + param->mode = kstrdup_const(prop->name + len, GFP_KERNEL); FWIW - I think you need to keep the logic in the previous loop into account because that's what is used to allocate param, it is not a given that param is valid at this stage if I am not mistaken - the previous loop checked: num = of_property_count_u32_elems(np, prop->name); if (num != 1 && num != 2) continue; Lorenzo > + if (!param->mode) > + continue; > + > + num = of_property_read_variable_u32_array(np, prop->name, magic, > + 1, ARRAY_SIZE(magic)); > + if (num < 0) { > + pr_warn("Failed to parse vendor reboot mode %s\n", > + param->mode); > + kfree_const(param->mode); > + continue; > + } > + > + /* Force reset type to be in vendor space */ > + param->reset_type = PSCI_1_1_RESET_TYPE_VENDOR_START | magic[0]; > + param->cookie = num > 1 ? magic[1] : 0; > + param++; > + num_psci_reset_params++; > + } > + > + return 0; > +} > +arch_initcall(psci_init_system_reset2_modes); > + > int __init psci_dt_init(void) > { > struct device_node *np; > > -- > 2.34.1 >