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[2a02:3100:94be:5400:80c7:5ea4:ed2f:1a59]) by smtp.googlemail.com with ESMTPSA id b1-20020a1709063ca100b007af0f0d2249sm15252848ejh.52.2023.01.18.13.55.41 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 18 Jan 2023 13:55:41 -0800 (PST) Message-ID: <83ab7926-2db3-ef60-8356-53bc517a22a8@gmail.com> Date: Wed, 18 Jan 2023 22:54:03 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.6.1 Subject: [PATCH v5 2/3] i2c: algo: bit: allow getsda to be NULL Content-Language: en-US From: Heiner Kallweit To: Rob Herring , Krzysztof Kozlowski , Wolfram Sang , Peter Rosin Cc: "linux-i2c@vger.kernel.org" , "devicetree@vger.kernel.org" References: <6f4b54d9-ab6d-a4d4-5142-27c89e03c6d2@gmail.com> In-Reply-To: <6f4b54d9-ab6d-a4d4-5142-27c89e03c6d2@gmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-i2c@vger.kernel.org This is in preparation of supporting write-only SDA in i2c-gpio. Signed-off-by: Heiner Kallweit --- v3: - check for adap->getsda in readbytes() - align warning message level for info on missing getscl/getsda v4: - handle SDA and SCL independently - properly handle case that SDA is NULL but SCL not --- drivers/i2c/algos/i2c-algo-bit.c | 77 +++++++++++++++----------------- 1 file changed, 35 insertions(+), 42 deletions(-) diff --git a/drivers/i2c/algos/i2c-algo-bit.c b/drivers/i2c/algos/i2c-algo-bit.c index fc90293af..eddf25b90 100644 --- a/drivers/i2c/algos/i2c-algo-bit.c +++ b/drivers/i2c/algos/i2c-algo-bit.c @@ -184,8 +184,9 @@ static int i2c_outb(struct i2c_adapter *i2c_adap, unsigned char c) /* read ack: SDA should be pulled down by slave, or it may * NAK (usually to report problems with the data we wrote). + * Always report ACK if SDA is write-only. */ - ack = !getsda(adap); /* ack: sda is pulled low -> success */ + ack = !adap->getsda || !getsda(adap); /* ack: sda is pulled low -> success */ bit_dbg(2, &i2c_adap->dev, "i2c_outb: 0x%02x %s\n", (int)c, ack ? "A" : "NA"); @@ -238,71 +239,55 @@ static int test_bus(struct i2c_adapter *i2c_adap) return -ENODEV; } + if (adap->getsda == NULL) + pr_info("%s: SDA is write-only, testing not possible\n", name); if (adap->getscl == NULL) - pr_info("%s: Testing SDA only, SCL is not readable\n", name); + pr_info("%s: SCL is write-only, testing not possible\n", name); - sda = getsda(adap); - scl = (adap->getscl == NULL) ? 1 : getscl(adap); + sda = adap->getsda ? getsda(adap) : 1; + scl = adap->getscl ? getscl(adap) : 1; if (!scl || !sda) { - printk(KERN_WARNING - "%s: bus seems to be busy (scl=%d, sda=%d)\n", - name, scl, sda); + pr_warn("%s: bus seems to be busy (scl=%d, sda=%d)\n", name, scl, sda); goto bailout; } sdalo(adap); - sda = getsda(adap); - scl = (adap->getscl == NULL) ? 1 : getscl(adap); - if (sda) { - printk(KERN_WARNING "%s: SDA stuck high!\n", name); + if (adap->getsda && getsda(adap)) { + pr_warn("%s: SDA stuck high!\n", name); goto bailout; } - if (!scl) { - printk(KERN_WARNING - "%s: SCL unexpected low while pulling SDA low!\n", - name); + if (adap->getscl && !getscl(adap)) { + pr_warn("%s: SCL unexpected low while pulling SDA low!\n", name); goto bailout; } sdahi(adap); - sda = getsda(adap); - scl = (adap->getscl == NULL) ? 1 : getscl(adap); - if (!sda) { - printk(KERN_WARNING "%s: SDA stuck low!\n", name); + if (adap->getsda && !getsda(adap)) { + pr_warn("%s: SDA stuck low!\n", name); goto bailout; } - if (!scl) { - printk(KERN_WARNING - "%s: SCL unexpected low while pulling SDA high!\n", - name); + if (adap->getscl && !getscl(adap)) { + pr_warn("%s: SCL unexpected low while pulling SDA high!\n", name); goto bailout; } scllo(adap); - sda = getsda(adap); - scl = (adap->getscl == NULL) ? 0 : getscl(adap); - if (scl) { - printk(KERN_WARNING "%s: SCL stuck high!\n", name); + if (adap->getscl && getscl(adap)) { + pr_warn("%s: SCL stuck high!\n", name); goto bailout; } - if (!sda) { - printk(KERN_WARNING - "%s: SDA unexpected low while pulling SCL low!\n", - name); + if (adap->getsda && !getsda(adap)) { + pr_warn("%s: SDA unexpected low while pulling SCL low!\n", name); goto bailout; } sclhi(adap); - sda = getsda(adap); - scl = (adap->getscl == NULL) ? 1 : getscl(adap); - if (!scl) { - printk(KERN_WARNING "%s: SCL stuck low!\n", name); + if (adap->getscl && !getscl(adap)) { + pr_warn("%s: SCL stuck low!\n", name); goto bailout; } - if (!sda) { - printk(KERN_WARNING - "%s: SDA unexpected low while pulling SCL high!\n", - name); + if (adap->getsda && !getsda(adap)) { + pr_warn("%s: SDA unexpected low while pulling SCL high!\n", name); goto bailout; } @@ -420,6 +405,10 @@ static int readbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg) unsigned char *temp = msg->buf; int count = msg->len; const unsigned flags = msg->flags; + struct i2c_algo_bit_data *adap = i2c_adap->algo_data; + + if (!adap->getsda) + return -EOPNOTSUPP; while (count > 0) { inval = i2c_inb(i2c_adap); @@ -670,11 +659,15 @@ static int __i2c_bit_add_bus(struct i2c_adapter *adap, if (ret < 0) return ret; - /* Complain if SCL can't be read */ - if (bit_adap->getscl == NULL) { + if (bit_adap->getsda == NULL) + dev_warn(&adap->dev, "Not I2C compliant: can't read SDA\n"); + + if (bit_adap->getscl == NULL) dev_warn(&adap->dev, "Not I2C compliant: can't read SCL\n"); + + if (bit_adap->getsda == NULL || bit_adap->getscl == NULL) dev_warn(&adap->dev, "Bus may be unreliable\n"); - } + return 0; }