| Message ID | 20241107-arm-psci-system_reset2-vendor-reboots-v8-3-e8715fa65cb5@quicinc.com |
|---|---|
| State | New |
| Headers | show |
| Series | Implement vendor resets for PSCI SYSTEM_RESET2 | expand |
Quoting Elliot Berman (2024-11-07 15:38:27) > 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. > > 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@broadcom.com> > Signed-off-by: Elliot Berman <quic_eberman@quicinc.com> > --- Reviewed-by: Stephen Boyd <swboyd@chromium.org>
On Fri, Nov 15, 2024 at 02:51:16PM +0100, Lorenzo Pieralisi wrote: > 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@broadcom.com> > > Signed-off-by: Elliot Berman <quic_eberman@quicinc.com> > > --- > > 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. If I expand the comment to: * try todo the vendor system_reset2 * If the reset fails or there wasn't a match on the command, * fall back to architectural resets. * Ignore reboot_mode enum to behave like setting a cookie, which don't * care about the reboot_mode. Help to address this concern? > > 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. > I went through the couple hundred drivers which register reboot and restart handlers. The majority don't care about reboot command nor reboot_mode enum. The few that do: Two drivers which I could find which care about the reboot command don't look at the reboot_mode argument. [1]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/firmware/efi/efibc.c?h=v6.11#n35 [2]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/power/reset/reboot-mode.c?h=v6.11#n42 One driver looks at the reboot command overrides the reboot_mode argument: [3]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/watchdog/pnx4008_wdt.c?h=v6.11#n125 I wasn't able to find any platform/arches which check the reboot_mode before reading the reboot command. > > /* > > @@ -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; of_property_read_variable_u32_array() performs effectively the same check. It returns -EOVERFLOW if it couldn't find enough (== 0) or too many values (>2). I currently have the added bonus of complaining in dmesg about the bad reboot mode property, instead of silently ignoring. - Elliot > > + 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 > >
On Fri, Nov 15, 2024 at 11:08:13AM -0800, Elliot Berman wrote: > On Fri, Nov 15, 2024 at 02:51:16PM +0100, Lorenzo Pieralisi wrote: > > 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@broadcom.com> > > > Signed-off-by: Elliot Berman <quic_eberman@quicinc.com> > > > --- > > > 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. > > If I expand the comment to: > > > * try todo the vendor system_reset2 > * If the reset fails or there wasn't a match on the command, > * fall back to architectural resets. > * Ignore reboot_mode enum to behave like setting a cookie, which don't > * care about the reboot_mode. /* * Check if the system supports vendor resets and issue * SYSTEM_RESET2 if the reboot command matches a vendor reset. * Ignore reboot_mode and execute SYSTEM_RESET2 with type and * cookie as defined by the firmware bindings. * * If the reset fails or there is not a match for the command * fall back to architectural resets; reset type detection in * this case will be done using reboot_mode. */ ? > Help to address this concern? Not entirely, sorry, I will get back to this. > > 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. > > > > I went through the couple hundred drivers which register reboot and > restart handlers. The majority don't care about reboot command nor > reboot_mode enum. The few that do: > > Two drivers which I could find which care about the reboot command don't > look at the reboot_mode argument. > > [1]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/firmware/efi/efibc.c?h=v6.11#n35 > [2]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/power/reset/reboot-mode.c?h=v6.11#n42 > > One driver looks at the reboot command overrides the reboot_mode > argument: > > [3]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/watchdog/pnx4008_wdt.c?h=v6.11#n125 Thanks for doing that, that helps. > I wasn't able to find any platform/arches which check the reboot_mode > before reading the reboot command. > > > > /* > > > @@ -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; > > of_property_read_variable_u32_array() performs effectively the same > check. It returns -EOVERFLOW if it couldn't find enough (== 0) or too > many values (>2). I currently have the added bonus of complaining in > dmesg about the bad reboot mode property, instead of silently ignoring. Right but we are dereferencing param (param->mode) before carrying out that check. Thanks, Lorenzo > > - Elliot > > > > + 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 > > >
On Mon, Nov 18, 2024 at 01:26:48PM +0100, Lorenzo Pieralisi wrote: > On Fri, Nov 15, 2024 at 11:08:13AM -0800, Elliot Berman wrote: > > On Fri, Nov 15, 2024 at 02:51:16PM +0100, Lorenzo Pieralisi wrote: > > > 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@broadcom.com> > > > > Signed-off-by: Elliot Berman <quic_eberman@quicinc.com> > > > > --- > > > > 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. > > > > If I expand the comment to: > > > > > > * try todo the vendor system_reset2 > > * If the reset fails or there wasn't a match on the command, > > * fall back to architectural resets. > > * Ignore reboot_mode enum to behave like setting a cookie, which don't > > * care about the reboot_mode. > > /* > * Check if the system supports vendor resets and issue > * SYSTEM_RESET2 if the reboot command matches a vendor reset. > * Ignore reboot_mode and execute SYSTEM_RESET2 with type and > * cookie as defined by the firmware bindings. > * > * If the reset fails or there is not a match for the command > * fall back to architectural resets; reset type detection in > * this case will be done using reboot_mode. > */ > > ? > > > Help to address this concern? > > Not entirely, sorry, I will get back to this. > > > > 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. > > > > > > > I went through the couple hundred drivers which register reboot and > > restart handlers. The majority don't care about reboot command nor > > reboot_mode enum. The few that do: > > > > Two drivers which I could find which care about the reboot command don't > > look at the reboot_mode argument. > > > > [1]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/firmware/efi/efibc.c?h=v6.11#n35 > > [2]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/power/reset/reboot-mode.c?h=v6.11#n42 > > > > One driver looks at the reboot command overrides the reboot_mode > > argument: > > > > [3]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/watchdog/pnx4008_wdt.c?h=v6.11#n125 > > Thanks for doing that, that helps. > > > I wasn't able to find any platform/arches which check the reboot_mode > > before reading the reboot command. > > > > > > /* > > > > @@ -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; > > > > of_property_read_variable_u32_array() performs effectively the same > > check. It returns -EOVERFLOW if it couldn't find enough (== 0) or too > > many values (>2). I currently have the added bonus of complaining in > > dmesg about the bad reboot mode property, instead of silently ignoring. > > Right but we are dereferencing param (param->mode) before carrying out that > check. > Ah, right, I see the problem. I'll send out another version after settling on the other part of the discussion! Thanks, Elliot
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) { /* @@ -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); + 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;
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. 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@broadcom.com> Signed-off-by: Elliot Berman <quic_eberman@quicinc.com> --- drivers/firmware/psci/psci.c | 104 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 104 insertions(+)