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[83.59.162.106]) by smtp.gmail.com with ESMTPSA id c1sm17196460wru.49.2020.10.10.08.52.56 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 10 Oct 2020 08:52:57 -0700 (PDT) Subject: Re: [PATCH v3 11/15] hw/misc/bcm2835_cprman: implement clock mux behaviour To: Luc Michel , qemu-devel@nongnu.org References: <20201010135759.437903-1-luc@lmichel.fr> <20201010135759.437903-12-luc@lmichel.fr> From: =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= Message-ID: <6982aced-ca14-73bf-48ff-7f739f2c389a@amsat.org> Date: Sat, 10 Oct 2020 17:52:56 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.3.1 MIME-Version: 1.0 In-Reply-To: <20201010135759.437903-12-luc@lmichel.fr> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=2a00:1450:4864:20::441; envelope-from=philippe.mathieu.daude@gmail.com; helo=mail-wr1-x441.google.com X-detected-operating-system: by eggs.gnu.org: No matching host in p0f cache. That's all we know. X-Spam_score_int: -19 X-Spam_score: -2.0 X-Spam_bar: -- X-Spam_report: (-2.0 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FORGED_FROMDOMAIN=0.001, FREEMAIL_FROM=0.001, HEADER_FROM_DIFFERENT_DOMAINS=0.249, NICE_REPLY_A=-0.207, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Peter Maydell , Havard Skinnemoen , Andrew Baumann , Paul Zimmerman , Niek Linnenbank , qemu-arm@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 10/10/20 3:57 PM, Luc Michel wrote: > A clock mux can be configured to select one of its 10 sources through > the CM_CTL register. It also embeds yet another clock divider, composed > of an integer part and a fractional part. The number of bits of each > part is mux dependent. > > Tested-by: Philippe Mathieu-Daudé > Signed-off-by: Luc Michel > --- > hw/misc/bcm2835_cprman.c | 53 +++++++++++++++++++++++++++++++++++++++- > 1 file changed, 52 insertions(+), 1 deletion(-) > > diff --git a/hw/misc/bcm2835_cprman.c b/hw/misc/bcm2835_cprman.c > index b22170f3bc..919a55aa23 100644 > --- a/hw/misc/bcm2835_cprman.c > +++ b/hw/misc/bcm2835_cprman.c > @@ -229,19 +229,70 @@ static const TypeInfo cprman_pll_channel_info = { > }; > > > /* clock mux */ > > +static bool clock_mux_is_enabled(CprmanClockMuxState *mux) > +{ > + return FIELD_EX32(*mux->reg_ctl, CM_CLOCKx_CTL, ENABLE); > +} > + > static void clock_mux_update(CprmanClockMuxState *mux) > { > - clock_update(mux->out, 0); > + uint64_t freq; > + uint32_t div, src = FIELD_EX32(*mux->reg_ctl, CM_CLOCKx_CTL, SRC); > + bool enabled = clock_mux_is_enabled(mux); > + > + *mux->reg_ctl = FIELD_DP32(*mux->reg_ctl, CM_CLOCKx_CTL, BUSY, enabled); > + > + if (!enabled) { > + clock_update(mux->out, 0); > + return; > + } > + > + freq = clock_get_hz(mux->srcs[src]); > + > + if (mux->int_bits == 0 && mux->frac_bits == 0) { > + clock_update_hz(mux->out, freq); > + return; > + } > + > + /* > + * The divider has an integer and a fractional part. The size of each part > + * varies with the muxes (int_bits and frac_bits). Both parts are > + * concatenated, with the integer part always starting at bit 12. > + * > + * 31 12 11 0 > + * ------------------------------ > + * CM_DIV | | int | frac | | > + * ------------------------------ > + * <-----> <------> > + * int_bits frac_bits > + */ > + div = extract32(*mux->reg_div, > + R_CM_CLOCKx_DIV_FRAC_LENGTH - mux->frac_bits, > + mux->int_bits + mux->frac_bits); > + > + if (!div) { > + clock_update(mux->out, 0); > + return; > + } > + > + freq = muldiv64(freq, 1 << mux->frac_bits, div); > + > + clock_update_hz(mux->out, freq); > } Much nicer now, thanks :) Reviewed-by: Philippe Mathieu-Daudé > > static void clock_mux_src_update(void *opaque) > { > CprmanClockMuxState **backref = opaque; > CprmanClockMuxState *s = *backref; > + CprmanClockMuxSource src = backref - s->backref; > + > + if (FIELD_EX32(*s->reg_ctl, CM_CLOCKx_CTL, SRC) != src) { > + return; > + } > > clock_mux_update(s); > } > > static void clock_mux_init(Object *obj) >