Messages in this thread | | | Subject | Re: [PATCH v4 10/10] mtd: rawnand: stm32_fmc2: get resources from parent node | From | Christophe Kerello <> | Date | Mon, 11 May 2020 16:19:47 +0200 |
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Hi Miquel,
On 5/11/20 2:58 PM, Miquel Raynal wrote: > Hi Christophe, > > Christophe Kerello <christophe.kerello@st.com> wrote on Mon, 11 May > 2020 14:47:09 +0200: > >> Hi Miquel, >> >> On 5/11/20 1:59 PM, Miquel Raynal wrote: >>> Hi Christophe, >>> >>> Christophe Kerello <christophe.kerello@st.com> wrote on Mon, 11 May >>> 2020 12:21:03 +0200: >>> >>>> Hi Miquel, >>>> >>>> On 5/11/20 11:18 AM, Miquel Raynal wrote: >>>>> Hi Christophe, >>>>> >>>>> Christophe Kerello <christophe.kerello@st.com> wrote on Wed, 6 May 2020 >>>>> 11:11:19 +0200: >>>>> >>>> FMC2 EBI support has been added. Common resources (registers base >>>>>> and clock) are now shared between the 2 drivers. It means that the >>>>>> common resources should now be found in the parent device when EBI >>>>>> node is available. >>>>>> >>>>>> Signed-off-by: Christophe Kerello <christophe.kerello@st.com> >>>>>> --- >>>>> >>>>> [...] >>>>> >>>> + >>>>>> +static bool stm32_fmc2_nfc_check_for_parent(struct platform_device *pdev) >>>>>> +{ >>>>>> + u32 i; >>>>>> + int nb_resources = 0; >>>>>> + >>>>>> + /* Count the number of resources in reg property */ >>>>>> + for (i = 0; i < pdev->num_resources; i++) { >>>>>> + struct resource *res = &pdev->resource[i]; >>>>>> + >>>>>> + if (resource_type(res) == IORESOURCE_MEM) >>>>>> + nb_resources++; >>>>>> + } >>>>>> + >>>>>> + /* Each CS needs 3 resources defined (data, cmd and addr) */ >>>>>> + if (nb_resources % 3) >>>>>> + return false; >>>>>> + >>>>>> + return true; >>>>>> +} >>>>> >>>>> This function looks fragile. Why not just checking the compatible >>>>> string of the parent node? >>>>> >> >>>> Yes, it is another way to check that we have an EBI parent node. >>>> >>>> In this implementation, I was checking the number of reg tuples. >>>> In case we have 6, it means that the register base address is defined in the parent node (EBI node). >>>> In case we have 7, it means that the register base address is defined in the current node (NFC node). >>> >>> Yes, I understand what you are doing, but I kind of dislike the logic. >>> Relying on the number of reg tuples is something that can be done (I >>> used it myself one time), but I think this is more a hack that you do >>> when you have no other way to differentiate. I guess the proper way >>> would be to look at the parent's compatible. If it matches what you >>> expect, then you can store the dev->of_node->parent->dev somewhere in >>> your controller's structure and then use it to initialize the clock and >>> regmap. This way you don't have to move anything else in the probe path. >>> >> >> OK, I will check the compatible string of the parent device using of_device_is_compatible API in v5. >> In case of the parent is found, I will add it in the structure of the controller (dev_parent). >> I will rely on this field only to get the common resources (the register base address and the clock) in the NFC node or in the EBI node. > > I had something slightly different in mind: what about setting a > default value to this field as being the controller's device itself. > This way, once it is set to either the parent device or the device > itself, you can use it "blindly" in your devm_clk_get/regmap_init calls? >
I will try to explain what I have in mind.
I will add a new field in the structure of the controller (not called dev_parent but cdev) struct device *cdev;
Then, at probe time, this field will be assigned: nfc->cdev = of_device_is_compatible(dev->parent->of_node, "bla bla") : dev->parent ? dev;
For the clock, it will be nfc->clk = devm_clk_get(nfc->cdev, NULL);
For the register base, I need to replace: res = platform_get_resource(pdev, IORESOURCE_MEM, 0); mmio = devm_ioremap_resource(dev, res); if (IS_ERR(mmio)) return PTR_ERR(mmio);
nfc->regmap = devm_regmap_init_mmio(dev, mmio, &stm32_fmc2_regmap_cfg); if (IS_ERR(nfc->regmap)) return PTR_ERR(nfc->regmap);
nfc->io_phys_addr = res->start;
With:
ret = of_address_to_resource(nfc->cdev->of_node, 0, &res); if (ret) return ret;
nfc->io_phys_addr = res.start;
nfc->regmap = device_node_to_regmap(nfc->cdev->of_node); if (IS_ERR(nfc->regmap)) return PTR_ERR(nfc->regmap);
I expect that you were thinking about something like this proposal.
Regards, Christophe Kerello.
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