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[83.53.161.74]) by smtp.gmail.com with ESMTPSA id l10sm7675863wru.59.2020.09.26.14.40.58 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 26 Sep 2020 14:40:58 -0700 (PDT) Subject: Re: [PATCH 10/14] hw/misc/bcm2835_cprman: implement clock mux behaviour To: Luc Michel , qemu-devel@nongnu.org References: <20200925101731.2159827-1-luc@lmichel.fr> <20200925101731.2159827-11-luc@lmichel.fr> From: =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= Message-ID: <76aae8af-dff0-b76f-cf04-0e3231eaf2bb@amsat.org> Date: Sat, 26 Sep 2020 23:40:57 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 MIME-Version: 1.0 In-Reply-To: <20200925101731.2159827-11-luc@lmichel.fr> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit 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=-0.213, 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 , qemu-arm@nongnu.org, Andrew Baumann Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 9/25/20 12:17 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 fractionnal part. The number of bits of each Typo "fractional". > part is mux dependant. Typo "dependent"? > > Signed-off-by: Luc Michel > --- > hw/misc/bcm2835_cprman.c | 43 +++++++++++++++++++++++++++++++++++++++- > 1 file changed, 42 insertions(+), 1 deletion(-) > > diff --git a/hw/misc/bcm2835_cprman.c b/hw/misc/bcm2835_cprman.c > index 8df2db0fd9..75bc11939b 100644 > --- a/hw/misc/bcm2835_cprman.c > +++ b/hw/misc/bcm2835_cprman.c > @@ -229,19 +229,60 @@ static const TypeInfo cprman_pll_channel_info = { > }; > > > /* clock mux */ > > +static bool clock_mux_is_enabled(CprmanClockMuxState *mux) > +{ > + return FIELD_EX32(*mux->reg_cm, CM_CLOCKx_CTL, ENABLE); > +} > + > static void clock_mux_update(CprmanClockMuxState *mux) > { > - clock_update(mux->out, 0); > + uint64_t freq, div; > + uint32_t src = FIELD_EX32(*mux->reg_cm, CM_CLOCKx_CTL, SRC); > + bool enabled = clock_mux_is_enabled(mux); > + > + *mux->reg_cm = FIELD_DP32(*mux->reg_cm, 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. > + */ > + div = mux->reg_cm[1] >> (R_CM_CLOCKx_DIV_FRAC_LENGTH - mux->frac_bits); > + div &= (1 << (mux->int_bits + mux->frac_bits)) - 1; > + > + freq = (freq << mux->frac_bits) / div; > + > + clock_update_hz(mux->out, freq); > } > > static void clock_mux_src_update(void *opaque) > { > CprmanClockMuxState **backref = opaque; > CprmanClockMuxState *s = *backref; > + CprmanClockMuxSource src = backref - s->backref; > + uint32_t current_src; > + > + current_src = FIELD_EX32(*s->reg_cm, CM_CLOCKx_CTL, SRC); > + > + if (current_src != src) { > + return; > + } > > clock_mux_update(s); > } > > static void clock_mux_init(Object *obj) >