From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tony Lindgren Subject: Re: [PATCH v2] pinctrl: single: support GPIO for bits pinctrl Date: Tue, 7 Jul 2015 00:42:29 -0700 Message-ID: <20150707074228.GP10705@atomide.com> References: <1436191025-9024-1-git-send-email-jun.nie@linaro.org> <20150706154205.GE10644@atomide.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from muru.com ([72.249.23.125]:33530 "EHLO muru.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754201AbbGGHmc (ORCPT ); Tue, 7 Jul 2015 03:42:32 -0400 Content-Disposition: inline In-Reply-To: Sender: linux-gpio-owner@vger.kernel.org List-Id: linux-gpio@vger.kernel.org To: Jun Nie Cc: Haojian Zhuang , Linus Walleij , linux-gpio@vger.kernel.org, Shawn Guo , "wan.zhijun" , Jason Liu * Jun Nie [150706 18:59]: > 2015-07-06 23:42 GMT+08:00 Tony Lindgren : > > * Jun Nie [150706 06:59]: > >> Support GPIO for one register control multiple pins case > >> with calculating register offset first, then bit offset. > >> > >> Signed-off-by: Jun Nie > >> --- > >> drivers/pinctrl/pinctrl-single.c | 22 ++++++++++++++++++---- > >> 1 file changed, 18 insertions(+), 4 deletions(-) > >> > >> diff --git a/drivers/pinctrl/pinctrl-single.c b/drivers/pinctrl/pinctrl-single.c > >> index 13b45f2..4f23ef0 100644 > >> --- a/drivers/pinctrl/pinctrl-single.c > >> +++ b/drivers/pinctrl/pinctrl-single.c > >> @@ -494,7 +494,7 @@ static int pcs_request_gpio(struct pinctrl_dev *pctldev, > >> struct pcs_device *pcs = pinctrl_dev_get_drvdata(pctldev); > >> struct pcs_gpiofunc_range *frange = NULL; > >> struct list_head *pos, *tmp; > >> - int mux_bytes = 0; > >> + int offset, mux_bytes = 0; > >> unsigned data; > >> > >> /* If function mask is null, return directly. */ > >> @@ -507,9 +507,23 @@ static int pcs_request_gpio(struct pinctrl_dev *pctldev, > >> || pin < frange->offset) > >> continue; > >> mux_bytes = pcs->width / BITS_PER_BYTE; > >> - data = pcs->read(pcs->base + pin * mux_bytes) & ~pcs->fmask; > >> - data |= frange->gpiofunc; > >> - pcs->write(data, pcs->base + pin * mux_bytes); > >> + if (pcs->bits_per_mux) { > >> + int pin_pos, byte_num, num_pins_in_register; > >> + > >> + num_pins_in_register = pcs->width / pcs->bits_per_pin; > >> + byte_num = (pcs->bits_per_pin * pin) / BITS_PER_BYTE; > >> + offset = (byte_num / mux_bytes) * mux_bytes; > >> + pin_pos = pin % num_pins_in_register; > >> + pin_pos *= pcs->bits_per_pin; > >> + data = pcs->read(pcs->base + offset) & > >> + ~(pcs->fmask << pin_pos); > >> + data |= (frange->gpiofunc & pcs->fmask) << pin_pos; > > > > I don't quite follow you here.. The pcs->fmask is for the whole register, > > so I think the fmask should be checked the same way in this case also: > > > > data = pcs->read(pcs->base + offset) & ~pcs->fmask; > > ... > > > > I don't think we can safely assume the fmask would behave differently > > in this case. > > My understanding to bits_per_mux flags here is that one 32bits > register shall control 16 pins if every pin takes 2 bits for function > config, where we shall have dts data: > "pinctrl-single,function-mask=<0x3>". Hmm function-mask needs to be for register-width to avoid confusion and to avoid trying to write to register reserved bits. It seems we need a new property here in addition to function-mask, and also need to correct the function-mask usage. The confusion seems to be introduced in 4e7e8017a80e ("pinctrl: pinctrl-single: enhance to configure multiple pins of different modules"). > In this case, pcs->fmask is 0x3 for all pins for we have only one copy > of pcs->fmask in driver. If we want to configure pin to gpio that > controlled by bit[3:2], we shall have below value set with shifting > mask to clear bit[3:2] first, then set desired value to configure it > as gpio. > data = pcs->read(pcs->base + offset) & > ~(pcs->fmask << pin_pos); > data = pcs->read(pcs->base + offset) & ~(0x3 << 2); Yeah OK we need some new property to deal with this. And need to fix up 4e7e8017a80e usage and ideally get rid of of all the if (pcs->bits_per_mux) else confusion. Regards, Tony