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Mon, 24 Aug 2020 12:24:27 -0700 (PDT) Subject: Re: Proper DT bindings for Broadcom's DMU node To: =?UTF-8?B?UmFmYcWCIE1pxYJlY2tp?= , "devicetree@vger.kernel.org" , Rob Herring , Vivek Unune Cc: BCM Kernel Feedback , Florian Fainelli References: <7da2db8f-66d0-24ec-d3eb-84247b383a06@gmail.com> From: Florian Fainelli Autocrypt: addr=f.fainelli@gmail.com; prefer-encrypt=mutual; keydata= mQGiBEjPuBIRBACW9MxSJU9fvEOCTnRNqG/13rAGsj+vJqontvoDSNxRgmafP8d3nesnqPyR xGlkaOSDuu09rxuW+69Y2f1TzjFuGpBk4ysWOR85O2Nx8AJ6fYGCoeTbovrNlGT1M9obSFGQ X3IzRnWoqlfudjTO5TKoqkbOgpYqIo5n1QbEjCCwCwCg3DOH/4ug2AUUlcIT9/l3pGvoRJ0E AICDzi3l7pmC5IWn2n1mvP5247urtHFs/uusE827DDj3K8Upn2vYiOFMBhGsxAk6YKV6IP0d ZdWX6fqkJJlu9cSDvWtO1hXeHIfQIE/xcqvlRH783KrihLcsmnBqOiS6rJDO2x1eAgC8meAX SAgsrBhcgGl2Rl5gh/jkeA5ykwbxA/9u1eEuL70Qzt5APJmqVXR+kWvrqdBVPoUNy/tQ8mYc nzJJ63ng3tHhnwHXZOu8hL4nqwlYHRa9eeglXYhBqja4ZvIvCEqSmEukfivk+DlIgVoOAJbh qIWgvr3SIEuR6ayY3f5j0f2ejUMYlYYnKdiHXFlF9uXm1ELrb0YX4GMHz7QnRmxvcmlhbiBG YWluZWxsaSA8Zi5mYWluZWxsaUBnbWFpbC5jb20+iGYEExECACYCGyMGCwkIBwMCBBUCCAME FgIDAQIeAQIXgAUCVF/S8QUJHlwd3wAKCRBhV5kVtWN2DvCVAJ4u4/bPF4P3jxb4qEY8I2gS 6hG0gACffNWlqJ2T4wSSn+3o7CCZNd7SLSC5BA0ESM+4EhAQAL/o09boR9D3Vk1Tt7+gpYr3 WQ6hgYVON905q2ndEoA2J0dQxJNRw3snabHDDzQBAcqOvdi7YidfBVdKi0wxHhSuRBfuOppu pdXkb7zxuPQuSveCLqqZWRQ+Cc2QgF7SBqgznbe6Ngout5qXY5Dcagk9LqFNGhJQzUGHAsIs hap1f0B1PoUyUNeEInV98D8Xd/edM3mhO9nRpUXRK9Bvt4iEZUXGuVtZLT52nK6Wv2EZ1TiT OiqZlf1P+vxYLBx9eKmabPdm3yjalhY8yr1S1vL0gSA/C6W1o/TowdieF1rWN/MYHlkpyj9c Rpc281gAO0AP3V1G00YzBEdYyi0gaJbCEQnq8Vz1vDXFxHzyhgGz7umBsVKmYwZgA8DrrB0M oaP35wuGR3RJcaG30AnJpEDkBYHznI2apxdcuTPOHZyEilIRrBGzDwGtAhldzlBoBwE3Z3MY 31TOpACu1ZpNOMysZ6xiE35pWkwc0KYm4hJA5GFfmWSN6DniimW3pmdDIiw4Ifcx8b3mFrRO BbDIW13E51j9RjbO/nAaK9ndZ5LRO1B/8Fwat7bLzmsCiEXOJY7NNpIEpkoNoEUfCcZwmLrU +eOTPzaF6drw6ayewEi5yzPg3TAT6FV3oBsNg3xlwU0gPK3v6gYPX5w9+ovPZ1/qqNfOrbsE FRuiSVsZQ5s3AAMFD/9XjlnnVDh9GX/r/6hjmr4U9tEsM+VQXaVXqZuHKaSmojOLUCP/YVQo 7IiYaNssCS4FCPe4yrL4FJJfJAsbeyDykMN7wAnBcOkbZ9BPJPNCbqU6dowLOiy8AuTYQ48m vIyQ4Ijnb6GTrtxIUDQeOBNuQC/gyyx3nbL/lVlHbxr4tb6YkhkO6shjXhQh7nQb33FjGO4P WU11Nr9i/qoV8QCo12MQEo244RRA6VMud06y/E449rWZFSTwGqb0FS0seTcYNvxt8PB2izX+ HZA8SL54j479ubxhfuoTu5nXdtFYFj5Lj5x34LKPx7MpgAmj0H7SDhpFWF2FzcC1bjiW9mjW HaKaX23Awt97AqQZXegbfkJwX2Y53ufq8Np3e1542lh3/mpiGSilCsaTahEGrHK+lIusl6mz Joil+u3k01ofvJMK0ZdzGUZ/aPMZ16LofjFA+MNxWrZFrkYmiGdv+LG45zSlZyIvzSiG2lKy kuVag+IijCIom78P9jRtB1q1Q5lwZp2TLAJlz92DmFwBg1hyFzwDADjZ2nrDxKUiybXIgZp9 aU2d++ptEGCVJOfEW4qpWCCLPbOT7XBr+g/4H3qWbs3j/cDDq7LuVYIe+wchy/iXEJaQVeTC y5arMQorqTFWlEOgRA8OP47L9knl9i4xuR0euV6DChDrguup2aJVU4hPBBgRAgAPAhsMBQJU X9LxBQkeXB3fAAoJEGFXmRW1Y3YOj4UAn3nrFLPZekMeqX5aD/aq/dsbXSfyAKC45Go0YyxV HGuUuzv+GKZ6nsysJ7kCDQRXG8fwARAA6q/pqBi5PjHcOAUgk2/2LR5LjjesK50bCaD4JuNc YDhFR7Vs108diBtsho3w8WRd9viOqDrhLJTroVckkk74OY8r+3t1E0Dd4wHWHQZsAeUvOwDM PQMqTUBFuMi6ydzTZpFA2wBR9x6ofl8Ax+zaGBcFrRlQnhsuXLnM1uuvS39+pmzIjasZBP2H UPk5ifigXcpelKmj6iskP3c8QN6x6GjUSmYx+xUfs/GNVSU1XOZn61wgPDbgINJd/THGdqiO iJxCLuTMqlSsmh1+E1dSdfYkCb93R/0ZHvMKWlAx7MnaFgBfsG8FqNtZu3PCLfizyVYYjXbV WO1A23riZKqwrSJAATo5iTS65BuYxrFsFNPrf7TitM8E76BEBZk0OZBvZxMuOs6Z1qI8YKVK UrHVGFq3NbuPWCdRul9SX3VfOunr9Gv0GABnJ0ET+K7nspax0xqq7zgnM71QEaiaH17IFYGS sG34V7Wo3vyQzsk7qLf9Ajno0DhJ+VX43g8+AjxOMNVrGCt9RNXSBVpyv2AMTlWCdJ5KI6V4 KEzWM4HJm7QlNKE6RPoBxJVbSQLPd9St3h7mxLcne4l7NK9eNgNnneT7QZL8fL//s9K8Ns1W t60uQNYvbhKDG7+/yLcmJgjF74XkGvxCmTA1rW2bsUriM533nG9gAOUFQjURkwI8jvMAEQEA AYkCaAQYEQIACQUCVxvH8AIbAgIpCRBhV5kVtWN2DsFdIAQZAQIABgUCVxvH8AAKCRCH0Jac RAcHBIkHD/9nmfog7X2ZXMzL9ktT++7x+W/QBrSTCTmq8PK+69+INN1ZDOrY8uz6htfTLV9+ e2W6G8/7zIvODuHk7r+yQ585XbplgP0V5Xc8iBHdBgXbqnY5zBrcH+Q/oQ2STalEvaGHqNoD UGyLQ/fiKoLZTPMur57Fy1c9rTuKiSdMgnT0FPfWVDfpR2Ds0gpqWePlRuRGOoCln5GnREA/ 2MW2rWf+CO9kbIR+66j8b4RUJqIK3dWn9xbENh/aqxfonGTCZQ2zC4sLd25DQA4w1itPo+f5 V/SQxuhnlQkTOCdJ7b/mby/pNRz1lsLkjnXueLILj7gNjwTabZXYtL16z24qkDTI1x3g98R/ xunb3/fQwR8FY5/zRvXJq5us/nLvIvOmVwZFkwXc+AF+LSIajqQz9XbXeIP/BDjlBNXRZNdo dVuSU51ENcMcilPr2EUnqEAqeczsCGpnvRCLfVQeSZr2L9N4svNhhfPOEscYhhpHTh0VPyxI pPBNKq+byuYPMyk3nj814NKhImK0O4gTyCK9b+gZAVvQcYAXvSouCnTZeJRrNHJFTgTgu6E0 caxTGgc5zzQHeX67eMzrGomG3ZnIxmd1sAbgvJUDaD2GrYlulfwGWwWyTNbWRvMighVdPkSF 6XFgQaosWxkV0OELLy2N485YrTr2Uq64VKyxpncLh50e2RnyAJ9Za0Dx0yyp44iD1OvHtkEI M5kY0ACeNhCZJvZ5g4C2Lc9fcTHu8jxmEkI= Message-ID: <30fe8a8d-34a7-2138-a823-f508a8250039@gmail.com> Date: Mon, 24 Aug 2020 12:24:21 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: devicetree-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On 8/20/20 5:38 AM, Rafał Miłecki wrote: > Hi Rob, could you help me/us with Northstar bindings design, please? > > On 04.05.2020 17:24, Rafał Miłecki wrote: >> I need some help with designing proper bindings for Broadcom's DMU >> block. We already have it partially covered but it's inconsistent, some >> cleanups were rejected and so I want to redesign it as it should be. >> >> DMU ("Device Management Unit") is a block that can be found on Broadcom >> iProc / Northstar devices. On Northstar it's mapped at: >> ranges = <0x1800c000 0x1000> >> >> It contains: >> 1. Few random registers, some of them shared by various hardware >>     blocks (and possibly hard to abstract?) >> 2. At least one sub-block with even more random registers >> >> Some of known DMU registers are: >> reg = <0x100 0x14>    CRU LCPLL control0 >> reg = <0x140 0x24>    CRU GENPLL >> reg = <0x164 0x04>    CRU_USB2_CONTROL >> reg = <0x180 0x04>    CRU_CLKSET_KEY >> reg = <0x184 0x04>    CRU_RESET >> reg = <0x1c0 0x24>    pinctrl >> reg = <0x2a0 0x04>    CRU_STRAPS_CTRL >> reg = <0x2c0 0x04>    PVTMON control0 >> (Broadcom never released a proper documentation) >> >> >> As you can see there are a few CRU registers (depending on a source it's >> a "Clock and Reset Unit" or "Central Resource Unit"). It's said to be >> separated block and was described by Scott (from Broadcom) as: "unit >> with a lot of random registers to perform various operations". >> >> As I said, there are also some shared registers: >> >> CRU_CLKSET_KEY is accessed by: >> 1. USB 2.0 PHY driver for (un)locking DMU PLL settings >> 2. GMAC for changing 2.66G line rate to 2Gbps >> >> CRU_STRAPS_CTRL needs to be accessed by: >> 1. USB 3.0 PHY driver for PHY connected to MDIO >> 2. PCIE driver for PHY connected to MDIO >> >> >> My initial idea was to have something like: >> >> dmu@1800c000 { >>      compatible = "simple-bus"; >>      ranges = <0 0x1800c000 0x1000>; >>      #address-cells = <1>; >>      #size-cells = <1>; >> >>      cru@100 { >>          compatible = "simple-bus"; >>          reg = <0x100 0x1a4>; >> >>          lcpll { ... }; >>          genpll { ... }; >>          reset { ... }; >>      }; >> }; >> >> but Rob noticed that "simple-bus" requires everything in DMU to have >> sub-nodes [0] [1]. > > "simple-bus" apparently is a no-way as some single registers may need to > be referenced using syscon. > > >> I thought it can be solved by using compatible = "syscon", "simple-mfd" >> and I even got one patch for that accepted [2] [3] (pinctrl). It seems >> it slipped through and was possibly a mistake. Another similar patch was >> rejected [4] [5] (bcm-ns-usb2-phy). >> >> What I tried to achieve was something like this: >> >> dmu@1800c000 { >>      compatible = "simple-bus"; >>      ranges = <0 0x1800c000 0x1000>; >>      #address-cells = <1>; >>      #size-cells = <1>; >> >>      cru: syscon@100 { >>          compatible = "syscon", "simple-mfd"; This should actually be a simple-bus no? >>          reg = <0x100 0x1a4>; >>          ranges; >>          #address-cells = <1>; >>          #size-cells = <1>; >> >>          lcpll0@0 { >>              #clock-cells = <1>; >>              compatible = "brcm,nsp-lcpll0"; >>              reg = <0x0 0x14>; >>          }; >> >>          genpll@40 { >>              #clock-cells = <1>; >>              compatible = "brcm,nsp-genpll"; >>              reg = <0x40 0x24>; >>          }; >> >>          pin-controller@c0 { >>              compatible = "brcm,bcm4708-pinmux"; >>              reg = <0xc0 0x24>; >>              reg-names = "cru_gpio_control"; >>          }; >> >>          thermal@1c0 { >>              compatible = "brcm,ns-thermal"; >>              reg = <0x1c0 0x10>; >>              #thermal-sensor-cells = <0>; >>          }; >>      }; >> }; >> >> cru-reset@??? { >>      compatible = "brcm,ns-cru-reset"; >>      syscon-cru = <&cru>; /* CRU_RESET */ >>      #reset-cells = <1>; >> }; >> >> usb2-phy@??? { >>      compatible = "brcm,ns-usb2-phy"; >>      syscon-cru = <&cru>; /* CRU_CLKSET_KEY */ >>      #phy-cells = <0>; >> }; >> >> (apparently it wasn't a good idea) > > Here I tried "syscon", "simple-mfd" which lets me: > 1. Have subnodes for all small hardware subblocks > 2. Reference single registers using syscon > but it appears I can't mix those two. It does not seem to me that there is an use case for syscon except for the USB2 PHY PLL which should arguably be a clock provider and the "DMP" register base used by the USB 3.0 PHY which should be a reset provider. -- Florian