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[193.12.47.89]) by smtp.gmail.com with ESMTPSA id q190sm4417402ljb.8.2021.02.02.11.17.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 02 Feb 2021 11:17:14 -0800 (PST) From: Tobias Waldekranz To: davem@davemloft.net, kuba@kernel.org Cc: george.mccollister@gmail.com, andrew@lunn.ch, vivien.didelot@gmail.com, f.fainelli@gmail.com, olteanv@gmail.com, netdev@vger.kernel.org Subject: [PATCH net-next] net: dsa: xrs700x: Correctly address device over I2C Date: Tue, 2 Feb 2021 20:16:45 +0100 Message-Id: <20210202191645.439-1-tobias@waldekranz.com> X-Mailer: git-send-email 2.17.1 Organization: Westermo Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On read, master should send 31 MSB of the register (only even values are ever used), followed by a 1 to indicate read. Then, reading two bytes, the device will output the register's value. On write, master sends 31 MSB of the register, followed by a 0 to indicate write, followed by two bytes containing the register value. Flexibilis' documentation (version 1.3) specifies the opposite polarity (#read/write), but the scope indicates that it is, in fact, read/#write. Signed-off-by: Tobias Waldekranz --- George, have you used the chip in I2C mode with the code that is on net-next now? I was not able to get the driver to even read the ID register correctly. drivers/net/dsa/xrs700x/xrs700x_i2c.c | 31 ++++++++++++--------------- 1 file changed, 14 insertions(+), 17 deletions(-) diff --git a/drivers/net/dsa/xrs700x/xrs700x_i2c.c b/drivers/net/dsa/xrs700x/xrs700x_i2c.c index a5f8883af829..16a46a78a037 100644 --- a/drivers/net/dsa/xrs700x/xrs700x_i2c.c +++ b/drivers/net/dsa/xrs700x/xrs700x_i2c.c @@ -10,33 +10,34 @@ #include "xrs700x.h" #include "xrs700x_reg.h" +struct xrs700x_i2c_cmd { + __be32 reg; + __be16 val; +} __packed; + static int xrs700x_i2c_reg_read(void *context, unsigned int reg, unsigned int *val) { struct device *dev = context; struct i2c_client *i2c = to_i2c_client(dev); - unsigned char buf[4]; + struct xrs700x_i2c_cmd cmd; int ret; - buf[0] = reg >> 23 & 0xff; - buf[1] = reg >> 15 & 0xff; - buf[2] = reg >> 7 & 0xff; - buf[3] = (reg & 0x7f) << 1; + cmd.reg = cpu_to_be32(reg | 1); - ret = i2c_master_send(i2c, buf, sizeof(buf)); + ret = i2c_master_send(i2c, (char *)&cmd.reg, sizeof(cmd.reg)); if (ret < 0) { dev_err(dev, "xrs i2c_master_send returned %d\n", ret); return ret; } - ret = i2c_master_recv(i2c, buf, 2); + ret = i2c_master_recv(i2c, (char *)&cmd.val, sizeof(cmd.val)); if (ret < 0) { dev_err(dev, "xrs i2c_master_recv returned %d\n", ret); return ret; } - *val = buf[0] << 8 | buf[1]; - + *val = be16_to_cpu(cmd.val); return 0; } @@ -45,17 +46,13 @@ static int xrs700x_i2c_reg_write(void *context, unsigned int reg, { struct device *dev = context; struct i2c_client *i2c = to_i2c_client(dev); - unsigned char buf[6]; + struct xrs700x_i2c_cmd cmd; int ret; - buf[0] = reg >> 23 & 0xff; - buf[1] = reg >> 15 & 0xff; - buf[2] = reg >> 7 & 0xff; - buf[3] = (reg & 0x7f) << 1 | 1; - buf[4] = val >> 8 & 0xff; - buf[5] = val & 0xff; + cmd.reg = cpu_to_be32(reg); + cmd.val = cpu_to_be16(val); - ret = i2c_master_send(i2c, buf, sizeof(buf)); + ret = i2c_master_send(i2c, (char *)&cmd, sizeof(cmd)); if (ret < 0) { dev_err(dev, "xrs i2c_master_send returned %d\n", ret); return ret;