From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mikko Perttunen Subject: Re: [PATCH v7 05/16] clk: tegra: Add DFLL DVCO reset control for Tegra124 Date: Fri, 13 Feb 2015 12:39:03 +0200 Message-ID: <54DDD447.8000404@kapsi.fi> References: <1420723339-30735-1-git-send-email-mikko.perttunen@kapsi.fi> <1420723339-30735-6-git-send-email-mikko.perttunen@kapsi.fi> <20150212141944.GK20811@tbergstrom-lnx.Nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20150212141944.GK20811-Rysk9IDjsxmJz7etNGeUX8VPkgjIgRvpAL8bYrjMMd8@public.gmane.org> Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Peter De Schrijver Cc: swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org, thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, gnurou-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, rjw-LthD3rsA81gm4RdzfppkhA@public.gmane.org, viresh.kumar-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, mturquette-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, pwalmsley-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org, vinceh-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org, pgaikwad-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-pm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, tuomas.tynkkynen-X3B1VOXEql0@public.gmane.org, Tuomas Tynkkynen List-Id: linux-tegra@vger.kernel.org On 02/12/2015 04:19 PM, Peter De Schrijver wrote: > On Thu, Jan 08, 2015 at 03:22:08PM +0200, Mikko Perttunen wrote: >> From: Paul Walmsley >> >> The DVCO present in the DFLL IP block has a separate reset line, >> exposed via the CAR IP block. This reset line is asserted upon SoC >> reset. Unless something (such as the DFLL driver) deasserts this >> line, the DVCO will not oscillate, although reads and writes to the >> DFLL IP block will complete. >> >> Thanks to Aleksandr Frid for identifying this and >> saving hours of debugging time. >> > > Should this be done as a reset driver? Probably through the already existing CAR reset driver. This reset doesn't fit well with the existing numbering scheme there, though. Perhaps a magic high-valued constant that represents it. > >> Signed-off-by: Paul Walmsley >> [ttynkkynen: ported to tegra124 from tegra114] >> Signed-off-by: Tuomas Tynkkynen >> Signed-off-by: Mikko Perttunen >> --- >> drivers/clk/tegra/clk-tegra124.c | 47 ++++++++++++++++++++++++++++++++++++++++ >> drivers/clk/tegra/clk.h | 3 +++ >> 2 files changed, 50 insertions(+) >> >> diff --git a/drivers/clk/tegra/clk-tegra124.c b/drivers/clk/tegra/clk-tegra124.c >> index f5f9bac..623b77f 100644 >> --- a/drivers/clk/tegra/clk-tegra124.c >> +++ b/drivers/clk/tegra/clk-tegra124.c >> @@ -31,6 +31,9 @@ >> #define CLK_SOURCE_CSITE 0x1d4 >> #define CLK_SOURCE_EMC 0x19c >> >> +#define RST_DFLL_DVCO 0x2f4 >> +#define DVFS_DFLL_RESET_SHIFT 0 >> + >> #define PLLC_BASE 0x80 >> #define PLLC_OUT 0x84 >> #define PLLC_MISC2 0x88 >> @@ -1399,6 +1402,50 @@ static void __init tegra124_clock_apply_init_table(void) >> tegra_init_from_table(init_table, clks, TEGRA124_CLK_CLK_MAX); >> } >> >> +/** >> + * tegra124_car_barrier - wait for pending writes to the CAR to complete >> + * >> + * Wait for any outstanding writes to the CAR MMIO space from this CPU >> + * to complete before continuing execution. No return value. >> + */ >> +static void tegra124_car_barrier(void) >> +{ >> + readl_relaxed(clk_base + RST_DFLL_DVCO); >> +} >> + >> +/** >> + * tegra124_clock_assert_dfll_dvco_reset - assert the DFLL's DVCO reset >> + * >> + * Assert the reset line of the DFLL's DVCO. No return value. >> + */ >> +void tegra124_clock_assert_dfll_dvco_reset(void) >> +{ >> + u32 v; >> + >> + v = readl_relaxed(clk_base + RST_DFLL_DVCO); >> + v |= (1 << DVFS_DFLL_RESET_SHIFT); >> + writel_relaxed(v, clk_base + RST_DFLL_DVCO); >> + tegra124_car_barrier(); >> +} >> +EXPORT_SYMBOL(tegra124_clock_assert_dfll_dvco_reset); >> + >> +/** >> + * tegra124_clock_deassert_dfll_dvco_reset - deassert the DFLL's DVCO reset >> + * >> + * Deassert the reset line of the DFLL's DVCO, allowing the DVCO to >> + * operate. No return value. >> + */ >> +void tegra124_clock_deassert_dfll_dvco_reset(void) >> +{ >> + u32 v; >> + >> + v = readl_relaxed(clk_base + RST_DFLL_DVCO); >> + v &= ~(1 << DVFS_DFLL_RESET_SHIFT); >> + writel_relaxed(v, clk_base + RST_DFLL_DVCO); >> + tegra124_car_barrier(); >> +} >> +EXPORT_SYMBOL(tegra124_clock_deassert_dfll_dvco_reset); >> + >> static void __init tegra124_clock_init(struct device_node *np) >> { >> struct device_node *node; >> diff --git a/drivers/clk/tegra/clk.h b/drivers/clk/tegra/clk.h >> index 4e458aa..def0ea4 100644 >> --- a/drivers/clk/tegra/clk.h >> +++ b/drivers/clk/tegra/clk.h >> @@ -629,6 +629,9 @@ void tegra114_clock_tune_cpu_trimmers_init(void); >> void tegra114_clock_assert_dfll_dvco_reset(void); >> void tegra114_clock_deassert_dfll_dvco_reset(void); >> >> +void tegra124_clock_assert_dfll_dvco_reset(void); >> +void tegra124_clock_deassert_dfll_dvco_reset(void); >> + >> typedef void (*tegra_clk_apply_init_table_func)(void); >> extern tegra_clk_apply_init_table_func tegra_clk_apply_init_table; >> >> -- >> 2.2.1 >>