Hi Andy,

FYI, the error/warning still remains.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   694d0d0bb2030d2e36df73e2d23d5770511dbc8d
commit: 4fcd504edbf7c793325511c2df8dcd083958e28a power: reset: add reboot mode driver
date:   6 weeks ago
config: um-allmodconfig (attached as .config)
compiler: gcc-6 (Debian 6.1.1-9) 6.1.1 20160705
reproduce:
        git checkout 4fcd504edbf7c793325511c2df8dcd083958e28a
        # save the attached .config to linux build tree
        make ARCH=um 

All errors (new ones prefixed by >>):

   drivers/mfd/syscon.c: In function 'of_syscon_register':
>> drivers/mfd/syscon.c:67:9: error: implicit declaration of function 'ioremap' [-Werror=implicit-function-declaration]
     base = ioremap(res.start, resource_size(&res));
            ^~~~~~~
   drivers/mfd/syscon.c:67:7: warning: assignment makes pointer from integer without a cast [-Wint-conversion]
     base = ioremap(res.start, resource_size(&res));
          ^
>> drivers/mfd/syscon.c:109:2: error: implicit declaration of function 'iounmap' [-Werror=implicit-function-declaration]
     iounmap(base);
     ^~~~~~~
   cc1: some warnings being treated as errors

vim +/ioremap +67 drivers/mfd/syscon.c

bdb0066d Pankaj Dubey  2014-09-30   61  
ca668f0e Philipp Zabel 2016-01-29   62  	if (of_address_to_resource(np, 0, &res)) {
ca668f0e Philipp Zabel 2016-01-29   63  		ret = -ENOMEM;
ca668f0e Philipp Zabel 2016-01-29   64  		goto err_map;
ca668f0e Philipp Zabel 2016-01-29   65  	}
ca668f0e Philipp Zabel 2016-01-29   66  
ca668f0e Philipp Zabel 2016-01-29  @67  	base = ioremap(res.start, resource_size(&res));
bdb0066d Pankaj Dubey  2014-09-30   68  	if (!base) {
bdb0066d Pankaj Dubey  2014-09-30   69  		ret = -ENOMEM;
bdb0066d Pankaj Dubey  2014-09-30   70  		goto err_map;
bdb0066d Pankaj Dubey  2014-09-30   71  	}
bdb0066d Pankaj Dubey  2014-09-30   72  
bdb0066d Pankaj Dubey  2014-09-30   73  	/* Parse the device's DT node for an endianness specification */
bdb0066d Pankaj Dubey  2014-09-30   74  	if (of_property_read_bool(np, "big-endian"))
bdb0066d Pankaj Dubey  2014-09-30   75  		syscon_config.val_format_endian = REGMAP_ENDIAN_BIG;
bdb0066d Pankaj Dubey  2014-09-30   76  	 else if (of_property_read_bool(np, "little-endian"))
bdb0066d Pankaj Dubey  2014-09-30   77  		syscon_config.val_format_endian = REGMAP_ENDIAN_LITTLE;
bdb0066d Pankaj Dubey  2014-09-30   78  
db2fb60c Damien Riegel 2015-11-30   79  	/*
db2fb60c Damien Riegel 2015-11-30   80  	 * search for reg-io-width property in DT. If it is not provided,
db2fb60c Damien Riegel 2015-11-30   81  	 * default to 4 bytes. regmap_init_mmio will return an error if values
db2fb60c Damien Riegel 2015-11-30   82  	 * are invalid so there is no need to check them here.
db2fb60c Damien Riegel 2015-11-30   83  	 */
db2fb60c Damien Riegel 2015-11-30   84  	ret = of_property_read_u32(np, "reg-io-width", &reg_io_width);
db2fb60c Damien Riegel 2015-11-30   85  	if (ret)
db2fb60c Damien Riegel 2015-11-30   86  		reg_io_width = 4;
db2fb60c Damien Riegel 2015-11-30   87  
db2fb60c Damien Riegel 2015-11-30   88  	syscon_config.reg_stride = reg_io_width;
db2fb60c Damien Riegel 2015-11-30   89  	syscon_config.val_bits = reg_io_width * 8;
ca668f0e Philipp Zabel 2016-01-29   90  	syscon_config.max_register = resource_size(&res) - reg_io_width;
db2fb60c Damien Riegel 2015-11-30   91  
bdb0066d Pankaj Dubey  2014-09-30   92  	regmap = regmap_init_mmio(NULL, base, &syscon_config);
bdb0066d Pankaj Dubey  2014-09-30   93  	if (IS_ERR(regmap)) {
bdb0066d Pankaj Dubey  2014-09-30   94  		pr_err("regmap init failed\n");
bdb0066d Pankaj Dubey  2014-09-30   95  		ret = PTR_ERR(regmap);
bdb0066d Pankaj Dubey  2014-09-30   96  		goto err_regmap;
bdb0066d Pankaj Dubey  2014-09-30   97  	}
bdb0066d Pankaj Dubey  2014-09-30   98  
bdb0066d Pankaj Dubey  2014-09-30   99  	syscon->regmap = regmap;
bdb0066d Pankaj Dubey  2014-09-30  100  	syscon->np = np;
bdb0066d Pankaj Dubey  2014-09-30  101  
bdb0066d Pankaj Dubey  2014-09-30  102  	spin_lock(&syscon_list_slock);
bdb0066d Pankaj Dubey  2014-09-30  103  	list_add_tail(&syscon->list, &syscon_list);
bdb0066d Pankaj Dubey  2014-09-30  104  	spin_unlock(&syscon_list_slock);
87d68730 Dong Aisheng  2012-09-05  105  
bdb0066d Pankaj Dubey  2014-09-30  106  	return syscon;
bdb0066d Pankaj Dubey  2014-09-30  107  
bdb0066d Pankaj Dubey  2014-09-30  108  err_regmap:
bdb0066d Pankaj Dubey  2014-09-30 @109  	iounmap(base);
bdb0066d Pankaj Dubey  2014-09-30  110  err_map:
bdb0066d Pankaj Dubey  2014-09-30  111  	kfree(syscon);
bdb0066d Pankaj Dubey  2014-09-30  112  	return ERR_PTR(ret);

:::::: The code at line 67 was first introduced by commit
:::::: ca668f0edfae65438c3f0a3ad5d3e59e3515915f mfd: syscon: Set regmap max_register in of_syscon_register

:::::: TO: Philipp Zabel <p.zabel@pengutronix.de>
:::::: CC: Lee Jones <lee.jones@linaro.org>

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