# Re: \[RESEND 1/4\] mfd: altera-sysmgr: Add SOCFPGA System Manager abstraction - From: Thor Thayer \ - Date: 2018-12-17 23:21:20 - List: netdev - Page: https://ratatoskr.run/netdev/2018/12/5465779 - Thread: https://ratatoskr.run/linux-arm-kernel/2018/11/5433196/t.md ```text Hi Arnd, On 12/14/18 6:36 AM, Arnd Bergmann wrote: > On Tue, Nov 13, 2018 at 5:03 PM [ref] wrote: >> >> From: Thor Thayer >> >> The SOCFPGA System Manager register block aggregate different >> peripheral functions into one place. >> On 32 bit ARM parts, the syscon framework fits this problem well. >> On 64 bit ARM parts, the System Manager can only be accessed by >> EL3 secure mode. Since a SMC call to EL3 is required, a new >> driver using regmaps similar to syscon was created that handles >> the SMC call. >> Since regmaps abstract out the underlying register access, the >> changes to drivers using System Manager are minimal. >> >> Signed-off-by: Thor Thayer >> --- >> Resend - update use_single_rw to use_single_read and >> use_single_write which was added in 4.20. > > Sorry for stepping in late here, I forgot to review it earlier and > Lee had to remind me to take a look. > :) Thank you for the review and comments! >> +static const struct regmap_config s10_sysmgr_regmap_cfg = { >> + .name = "s10_sysmgr", >> + .reg_bits = 32, >> + .reg_stride = 4, >> + .val_bits = 32, >> + .reg_read = s10_protected_reg_read, >> + .reg_write = s10_protected_reg_write, >> + .fast_io = true, >> + .use_single_read = true, >> + .use_single_write = true, >> +}; > > The new regmap seems fine to me, that looks like a good way > of abstracting the two hardware methods. > >> +/** >> + * socfpga_is_s10 >> + * Determine if running on Stratix10 platform. >> + * Return: True if running Stratix10, otherwise false. >> + */ >> +static int socfpga_is_s10(void) >> +{ >> + return of_machine_is_compatible("altr,socfpga-stratix10"); >> +} > > I don't really like the way you are checking for a specific here > here though, that is something that should only be done in > an absolute emergency when there is no way of fixing the > device tree files. > > Since this is a new driver for a device that is not used in > mainline kernels yet (AFAICT), let's fix the binding and add > a proper detection method here. > Thank you. I'm not completely clear on this. Are you saying this function should test for a new compatible that is assigned to Stratix10 in the binding ("altr,sys-mgr-s10") instead of the machine name? >> + >> +/** >> + * of_sysmgr_register >> + * Create and register the Altera System Manager regmap. >> + * Return: Pointer to new sysmgr on success. >> + * Pointer error on failure. >> + */ >> +static struct altr_sysmgr *of_sysmgr_register(struct device_node *np) >> +{ >> + struct altr_sysmgr *sysmgr; >> + struct regmap *regmap; >> + u32 reg_io_width; >> + int ret; >> + struct regmap_config sysmgr_config = s10_sysmgr_regmap_cfg; >> + struct resource res; >> + >> + if (!of_device_is_compatible(np, "altr,sys-mgr")) >> + return ERR_PTR(-EINVAL); >> + >> + sysmgr = kzalloc(sizeof(*sysmgr), GFP_KERNEL); >> + if (!sysmgr) >> + return ERR_PTR(-ENOMEM); >> + >> + if (of_address_to_resource(np, 0, &res)) { >> + ret = -ENOMEM; >> + goto err_map; >> + } >> + >> + /* Need physical address for SMCC call */ >> + sysmgr->base = (void __iomem *)res.start; > > The cast here seems really ugly. Instead of mixinx up > address spaces, how about adding a resource_size_t > member in the sysmgr structure? > Yes. I will change. >> + * search for reg-io-width property in DT. If it is not provided, >> + * default to 4 bytes. regmap_init will return an error if values >> + * are invalid so there is no need to check them here. >> + */ >> + ret = of_property_read_u32(np, "reg-io-width", ®_io_width); >> + if (ret) >> + reg_io_width = 4; > > How likely is it that this would ever not be four bytes? It looks > like you just copied this from syscon, but it really should not be > needed. > Yes. I will change. >> +struct regmap *altr_sysmgr_node_to_regmap(struct device_node *np) >> +{ >> + struct altr_sysmgr *sysmgr = NULL; >> + >> + if (!socfpga_is_s10()) >> + return syscon_node_to_regmap(np); > > Why do you go through syscon here? Doesn't this add a lot of complexity? > > I'd suggest using regmap_init_mmio() directly and open-coding the > initialization you need as you do for the s10 case. > Yes. It is more complex but I was concerned about re-implementing large parts of syscon for the ARM32 case. However, re-implementing it will simplify the driver and keep both ARM32 and ARM64 together. Thanks for the suggestion - I will change it. >> + if (!p_sysmgr) >> + sysmgr = of_sysmgr_register(np); >> + else >> + sysmgr = p_sysmgr; >> + >> + if (IS_ERR_OR_NULL(sysmgr)) >> + return ERR_CAST(sysmgr); > > Don't use IS_ERR_OR_NULL(), it's just a sign that your API > is bad. Instead, define the interface either so that you > always return NULL on error or that you always return an > PTR_ERR() value on error. > OK. I will change this. >> +struct regmap *altr_sysmgr_regmap_lookup_by_compatible(const char *s) >> +{ >> + struct device_node *sysmgr_np; >> + struct regmap *regmap; >> + >> + if (!socfpga_is_s10()) >> + return syscon_regmap_lookup_by_compatible(s); >> + >> + sysmgr_np = of_find_compatible_node(NULL, NULL, s); >> + if (!sysmgr_np) >> + return ERR_PTR(-ENODEV); >> + >> + regmap = altr_sysmgr_node_to_regmap(sysmgr_np); >> + of_node_put(sysmgr_np); >> + >> + return regmap; >> +} >> +EXPORT_SYMBOL_GPL(altr_sysmgr_regmap_lookup_by_compatible); > > That should not be needed, just look it up by phandle and be done > with it. Again, lookup by compatible should only be needed for > compatibility with old DTB files, but you should be able to fix the > binding so you always have a phandle to the correct node here, > at least for the s10 case. > > For the older chips with existing DTs, I guess drivers can fall back to > the syscon method directly. > >> +EXPORT_SYMBOL_GPL(altr_sysmgr_regmap_lookup_by_pdevname); > > Same comment. > > Arnd > Yes. I will make these changes. Thanks so much for the review! ```