Re: [PATCH v2 0/3] Add the efuse driver on rockchip platform

On 2015年08月05日 00:11, Srinivas Kandagatla wrote:

Hi Shunqian,

Sorry for delay in reply, I was on Holidays..

Thanks for testing.

On 31/07/15 10:27, Shunqian Zheng wrote:

quoted

1. Without the following diff, `hexdump
/sys/bus/nvmem/devices/rockchip-efuse0/nvmem` is wrong with "INVALID
ARGUMENT":

+++ b/drivers/nvmem/core.c

@@ -67,7 +67,7 @@ static ssize_t bin_attr_nvmem_read(struct file *filp,

struct kobject *kobj,
         int rc;

         /* Stop the user from reading */
-       if (pos > nvmem->size)
+       if (pos > nvmem->size - 1)
                 return 0;

Yes, this should have been something like this
-       if (pos > nvmem->size)
+       if (pos >= nvmem->size)
                return 0;

We can send a fix on top of v9 once its merged.

quoted

         if (pos + count > nvmem->size)

RK3288-efuse has  32 x 8bit regs, in dts "reg = <0xffb40000 0x20>;"
Here is the message dump from nvmem_device:
[    2.158314] nvmem:
[    2.158314]           name (null)
[    2.158314]           stride 1
[    2.158314]           word_size 1
[    2.158314]           ncells 0
[    2.158314]           id 0
[    2.158314]           users 0
[    2.158314]           size 32
[    2.158314]           read_only 0

Do you think there is a leak or I'm messing up ?

2. About the read operation, eFuse data can be read during device
probe() and cached, OR,
     read from eFuse when needed every time. I prefer the second one but
then, the clock of eFuse may be
     gated. So before/after reading I have to enable/disable clk like :
           devm_clk_get(dev, "hclk_efuse256");
     The trouble is I can't find a way to get the "dev" hander in :
           static int rockchip_efuse_read(void *context, const void
*reg, size_t reg_size, void *val, size_t val_size)
     I am appreciated if you can give some advice.

May be you should use regmap_init_mmio_clk() instead of regmap_init_mmio() it will take care of clks.

Thank you for you reply.
Although the regmap_init_mmio_clk() and it's series interface deal with the clks, but
MMIO uses its own regmap_bus{}, while the eFuse of RK3X need special read/write
callback functions.

I still can't find a good way to resolve this. Can you help?

Shunqian

quoted

     Or, do you think it's reasonable to add hooks before/after read in
nvmem/core.c like :
           +       before_read(dev, ...);
                    rc = regmap_raw_read(nvmem->regmap, pos, buf, count);
           +       after_read(dev, ...);

quoted

3. In the /sys/bus/nvmem/devices/rockchip-efuse0/, there are files:
          /sys/devices/platform/ffb40000.efuse/rockchip-efuse0 # ls
          nvmem      of_node    power      subsystem  uevent
     Do you have a plan to add the nvmem consumers to /sys/ in nvmem
framework?

yes, Am waiting for the framework to be merged, I have plans to add this feature.

quoted

     For example,  in dts defined the "cpu_leakage":
         efuse: efuse@ffb40000 {
                 compatible = "rockchip,rk3x-efuse";
                 reg = <0xffb40000 0x20>;
                 #address-cells = <1>;
                 #size-cells = <1>;
                 clocks = <&cru PCLK_EFUSE256>;
                 clock-names = "pclk_efuse_256";

                 cpu_leakage: cpu_leakage {
                         reg = <0x17 0x1>;
                 };
         };
    Then nvmem exposes the "cpu_leakage" file in /sys which can be
read/write.

--srini