Re: [PATCH v2 3/8] gpio: pci-idio-16: Implement get_multiple callback

[kbuild test robot]

Hi William,

I love your patch! Perhaps something to improve:

[auto build test WARNING on v4.16-rc4]
[also build test WARNING on next-20180316]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/William-Breathitt-Gray/Implement-get_multiple-for-ACCES-and-PC-104-drivers/20180317-224135
reproduce:
        # apt-get install sparse
        make ARCH=x86_64 allmodconfig
        make C=1 CF=-D__CHECK_ENDIAN__


sparse warnings: (new ones prefixed by >>)

   drivers/gpio/gpio-pci-idio-16.c:139:17: sparse: undefined identifier 'word_mask'
   drivers/gpio/gpio-pci-idio-16.c:140:22: sparse: undefined identifier 'word_mask'
>> drivers/gpio/gpio-pci-idio-16.c:120:27: sparse: dereference of noderef expression
   drivers/gpio/gpio-pci-idio-16.c:120:52: sparse: dereference of noderef expression
   drivers/gpio/gpio-pci-idio-16.c:121:27: sparse: dereference of noderef expression
   drivers/gpio/gpio-pci-idio-16.c:121:51: sparse: dereference of noderef expression
>> drivers/gpio/gpio-pci-idio-16.c:139:17: sparse: generating address of non-lvalue (3)
   drivers/gpio/gpio-pci-idio-16.c: In function 'idio_16_gpio_get_multiple':
   drivers/gpio/gpio-pci-idio-16.c:139:3: error: 'word_mask' undeclared (first use in this function); did you mean 'port_mask'?
      word_mask = mask[word_index] & (port_mask << word_offset);
      ^~~~~~~~~
      port_mask
   drivers/gpio/gpio-pci-idio-16.c:139:3: note: each undeclared identifier is reported only once for each function it appears in
   drivers/gpio/gpio-pci-idio-16.c:146:24: warning: passing argument 1 of 'ioread8' discards 'const' qualifier from pointer target type [-Wdiscarded-qualifiers]
      port_state = ioread8(ports + i);
                           ^~~~~
   In file included from arch/x86/include/asm/io.h:223:0,
                    from arch/x86/include/asm/realmode.h:15,
                    from arch/x86/include/asm/acpi.h:33,
                    from arch/x86/include/asm/fixmap.h:19,
                    from arch/x86/include/asm/apic.h:10,
                    from arch/x86/include/asm/smp.h:13,
                    from arch/x86/include/asm/mmzone_64.h:11,
                    from arch/x86/include/asm/mmzone.h:5,
                    from include/linux/mmzone.h:912,
                    from include/linux/gfp.h:6,
                    from include/linux/idr.h:16,
                    from include/linux/kernfs.h:14,
                    from include/linux/sysfs.h:16,
                    from include/linux/kobject.h:20,
                    from include/linux/device.h:16,
                    from drivers/gpio/gpio-pci-idio-16.c:16:
   include/asm-generic/iomap.h:29:21: note: expected 'void *' but argument is of type 'const u8 * {aka const unsigned char *}'
    extern unsigned int ioread8(void __iomem *);
                        ^~~~~~~
   drivers/gpio/gpio-pci-idio-16.c:116:16: warning: unused variable 'mask_word' [-Wunused-variable]
     unsigned long mask_word;
                   ^~~~~~~~~

vim +120 drivers/gpio/gpio-pci-idio-16.c

   106	
   107	static int idio_16_gpio_get_multiple(struct gpio_chip *chip,
   108		unsigned long *mask, unsigned long *bits)
   109	{
   110		struct idio_16_gpio *const idio16gpio = gpiochip_get_data(chip);
   111		size_t i;
   112		const unsigned int gpio_reg_size = 8;
   113		unsigned int bits_offset;
   114		size_t word_index;
   115		unsigned int word_offset;
   116		unsigned long mask_word;
   117		const unsigned long port_mask = GENMASK(gpio_reg_size, 0);
   118		unsigned long port_state;
   119		const u8 __iomem ports[] = {
 > 120			idio16gpio->reg->out0_7, idio16gpio->reg->out8_15,
   121			idio16gpio->reg->in0_7, idio16gpio->reg->in8_15
   122		};
   123	
   124		/* clear bits array to a clean slate */
   125		bitmap_zero(bits, chip->ngpio);
   126	
   127		/* get bits are evaluated a gpio port register at a time */
   128		for (i = 0; i < ARRAY_SIZE(ports); i++) {
   129			/* gpio offset in bits array */
   130			bits_offset = i * gpio_reg_size;
   131	
   132			/* word index for bits array */
   133			word_index = BIT_WORD(bits_offset);
   134	
   135			/* gpio offset within current word of bits array */
   136			word_offset = bits_offset % BITS_PER_LONG;
   137	
   138			/* mask of get bits for current gpio within current word */
 > 139			word_mask = mask[word_index] & (port_mask << word_offset);
   140			if (!word_mask) {
   141				/* no get bits in this port so skip to next one */
   142				continue;
   143			}
   144	
   145			/* read bits from current gpio port */
   146			port_state = ioread8(ports + i);
   147	
   148			/* store acquired bits at respective bits array offset */
   149			bits[word_index] |= port_state << word_offset;
   150		}
   151	
   152		return 0;
   153	}
   154	

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